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Full text of "Collected reprints, Essa Institute for Oceanography"

U.S. DEPARTMENT OF COMMERCE/Environmental Science Services Administration 



COLLECTED 



REPRINTS 



ESSA INSTITUTE FOR OCEANOGRAPHY 



-<tAENTp^ 




Sc 'tHCE S£R^ V 




ATLANTIC-PACIFIC 
OCEANOGRAPHIC LABORATORIES 



1967 




U.S. DEPARTMENT OF COMMERCE 
Maurice H. Stems, Secretary 

ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION 

Robert M. White, Administrator 
RESEARCH LABORATORIES 
George S. Benton, Director 



Collected Reprints 
Essa Institute for Oceanography 

1967 



Atlantic Oceanographic Laboratories 
Miami, Florida 



Pacific Oceanographic Laboratories 
Seattle, Washington 



For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 

Price $3.00 



FOREWORD 



The effectiveness of any research organization is indi- 
cated not by the size of its budget, nor by the size and 
impressiveness of its building, not even by the number of 
Ph.D. scientists it includes on its staff. Rather a research 
organization should be judged on the contribution it makes to 
the growing fund of human knowledge. One indication of this 
is the published papers of its scientists. 

New knowledge, however, is of relatively little use 
unless it is disseminated so those that can benefit from it 
know it exists. To these ends the various published papers 
of the members of the Institute for Oceanography of the 
Environmental Science Services Administration, U. S. 
Department of Commerce, have been compiled into this 
volume for the year 1967. 

In November of 1967, the ESSA Institute for Ocean- 
ography, became two separate activities, the Atlantic Ocean- 
ographic Laboratories (Miami, Florida) and the Pacific 
Oceanographic Laboratories (Seattle, Washington). Collected 
reprints for 1968 will reflect this change. 



Harris B. Stewart, Jr. 

Director 

ESSA Institute for Oceanography 



11 



TABLE OF CONTENTS 
METEOROLOGICAL OCEANOGRAPHY 

1. Harris, D. Lee, 

(a) A critical survey of the storm surge protection problem, 

(b) The drag coefficient between wind and water, 

Proc. Eleventh Pacific Science Congress in Vol. 2, Oceanography, 
Tokyo. 

2. Jelsnianski, Chester P. , Numerical computations of storm surges 

with bottom stress, Monthly Weather Rev. _9_b, No. 11, 740-75b. 

3. Kuhn, Peter M. , and James D. McFadden, Atmospheric water vapor 

profiles derived from remote-sensing radiometer measurements, 
Monthly Weather Rev. _9_5, No. 8, 5bb-bb8. 

4. Lettau, Bernhard, Thermally and frictionally produced wind shear 

in the planetary boundary layer at Little America, Antarctica, 
Monthly Weather Rev. _9_b, No. 9, b2Y-b34. 

5. McFadden, James D. , Sea- surface temperatures in the wake of 

Hurricane Betsy (19bb), Monthly Weather Rev. _9_b, No. b, 
299-302. 

b. McFadden, James D. , and John W. Wilkerson, Compatibility of 
aircraft and shipborne instruments used in Air-Sea Interaction 
Research, Monthly Weather Rev. 9j>, No. 12, 9ib-94l. 

7. McFadden, James D. , and Robert A. Ragotzkie, Climatological 

significance of albedo in Central Canada, J. Geophys. Res. 72 , 
No. 4, Il3b-ll43. 



MARINE GEOLOGY AND GEOPHYSICS 



8. Anikouchine, William A. , Dissolved chemical substances in com- 

pacting marine sediments, J. Geophys. Res. J72, No. 2, 
505-509. 

9. Anikouchine, William A. , and Hsing-Yi Ling, Evidence of turbidite 

accumulation in trenches in the Indo-Pacific region, Marine 
Geol. 5, 141-154. 



in 



10. Burns, Robert E. , and Paul J. Grim, Heat flow in the Pacific off 

Central California, J. Geophys. Res T2, No. 24, 6239-6247. 

11. Dietz, Roberts., Astroblemes, McGraw-Hill Yearbook of Science 

and Technology, 109-111 (McGraw-Hill Book Co. , Inc., New 
York, N.Y.). 

12. Dietz, Robert S. , Craters and legends, Medical Opinion and Rev. _3, 

No. 1, 50-57. 

13. Dietz, Robert S. , More about continental drift, Sea Frontiers 1 3 , 

No. 2, 66-82. 

14. Dietz, Robert S. , Passive continents, spreading sea floors and 

continental rises; A reply, Am, J. Sci. 265 , 231-237. 

15. Dietz, Robert S. , Shatter cone orientation at Gosses Bluff astro- 

bleme, Nature 2l6_, 1082-1084, Dec. 1967. 

16. Harbison, R. N. , De Soto Canyon reveals salt trends, Oil and Gas 

J. 6_5, No. 8, 124-128. 

17. Harrison, W. , Environmental effects of dredging and soil deposition, 

Proc. World Dredging Conf. , 535-539. 

18. Harrison, W. , and A. M. Richardson, Jr. , Plate-load tests on 

sandy marine sediments, Lower Chesapeake Bay, Marine 
Geotechnique, 274-290 (Univ. of Illinois Press, Urbana, 111.). 

19. Keller, G. H. Pleistocene-recent boundary in the Malacca Strait, 

Southeast Asia, Proc. Seventh Internatl. Sedimentological 
Congress. 

20. Keller, George H. , and Adrian F. Richards, Sediments of the 

Malacca Strait, Southwest Asia, J. Sed. Pet. _37, No. 1, 102-127. 

21. Ling, Hsing-Yi, and W. A. Anikouchine, Some spumellarian radio- 

laria from Java, Philippines, and Mariana trenches, J. Paleon- 
tology 41_, No. 6, 1481-1491. 

22. Malloy, R. J. , Vertical crustal movement associated with the 1964 

Alaskan earthquake, Proc. Eleventh Pacific Science Congress 
in Vol. 2 Oceanography, Tokyo. 



IV 



2 3. Perry, R. B. , and Haven Nichols, Submarine geology of the Aleutian 
Arc, Alaska, Proc. Eleventh Pacific Science Congress in Vol. 2 
Oceanography, Tokyo. 

24. Peter, G. , D. Elvers, and O. Dewald, Results from a geophysical 
survey in the North-East Pacific Ocean, Proc. Eleventh Pacific 
Science Congress in Vol. 2 Oceanography, Tokyo. 



25. Sokolowski, T. J., andG. R. Miller, Automated epicenter locations 

from a quadripartite array, Bull. Seismol. Soc. Am. _57, No. 2, 
269-275. 

26. von Huene, Roland, Richard J. Malloy, George G. Shor, Jr. , and 

Pierre St-Amand., Geological structures in the aftershock region 
of the 19&4 Alaskan earthquake, J. Geophys. Res. _72, No. 14, 
3649-3660. 

27. "Weeks, L. A., R. N. Harbison, andG. Peter, Island arc system 

in Andaman Sea, Am. Assoc. Petrol. Geol. Bull. 51_, No. 9, 
1803-1315. 



PHYSICAL OCEANOGRAPHY 

28. Butler, J. P. , Double-humped waves on a sloping beach, HIG-67-16, 

ESSA/JTRE-2 - Univ. of Hawaii. 

29. Chew, Frank, On the cross-stream variation of the k-factor for 

geomagnetic electrokinetograph data from the Florida current 
off Miami, Limn, and Ocean. 12_, No. 1, 73-78. 

30. Gassaway, John D. , New method for Boron determination in sea 

water and some preliminary results, Internatl. J. Ocean, and 
Limn. !_, No. 2, 85-90. 

31. Munk, W. H. , and B. D. Zetler, Deep-sea tides: A program, 

Sci. 158_, No. 3003, 884-886. 

32. Nelson, Raymond M. , Sensing ocean currents from space: Ocean 

Industry 2, No. 5, 40-42. 

33. Seelinger, P. E. , R. A. Wallston, B. H. Erickson, J. E. 

Master son, and W. E. Hoehne, An oceanographic data collection 
system, Trans. Second Internatl. Buoy Technol. Symp. , Marine 
Technol. Soc, Washington, D. C. 



34. Vitousek, M. J., and G. R. Miller, Low-frequency wave study in 

the Meso-deep ocean, HIG-67-11, ESSA/JTRE - Univ. of Hawaii. 

35. Zetler, Bernard D. , Tides and other long period waves, U.S.Natl. 

Rept. 1963-1967 to 14th Gen. Assembly, IUGG, Trans. A.G.U. , 
591-595. 

36. Zetler, B. D. , and G. W. Lennon, Some comparative tests of tidal 

analytical processes, Internatl. Hydro. Rev. _44, No. 1, 139-147. 

37. Zetler, B. D. , and R. A. Cummings, A harmonic method for pre- 

dicting shallow water tides, Proc. Eleventh Pacific Science 
Congress in Vol. 2, Oceanography, Tokyo. 

38. Zetler, B. D. , and R. A. Cummings, A harmonic method for pre- 

dicting shallow water tides, J. Marine Res. _2_5, No. 1, 10 3-114. 

GENERAL 

39. Schuldt, M. D. , C. E. Cook, and B. W. Hale, Photogrammetry 

applied to photography at the bottom, Part of Deep Sea Photo- 
graphy, ed. J. B. Her sey, (Johns Hopkins Univ. Press, 
Baltimore, Md.). 

40. Stewart, Harris B. , Jr. , Seafloor Geology 1968 Yearbook Directory, 

Oceanol. Internatl., June, 30-31. 

41. Stewart, Harris B. , Jr., Killer at the seashore, ESSA World_2, 

No. 3, 30-31, U. S. Dept. of Commerce, Rockville, Md. 

42. Stewart, Harris B. , Jr., Sea science ships, The Miamian, 

Sept. 1967, p. 27. 

PUBLICATIONS NOT INCLUDED 



GENERAL 

Stewart, Harris B. , Jr. , True-life adventures: dive to a mountain- 
top, Summer Senior Weekly Reader 6_, No. 5, 6. 

Stewart, Harris B. , Jr., Underwater worlds of tomorrow, Presidents 
Assoc. , Inc. 



VI 



lA 



Reprinted from PROCEEDINGS THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2 Oceanography, Tokyo, 1966 



-13- 
A CRITICAL SURVEY OP THE STORM SURGE PROTECTION PROBLEM 

D. Lee Harris Institute for Oceanography Environmental Science Services 
Administration, United States of America 

The goal of a disaster warning service is to provide the maximum 
protection to the public with a minimum of inconvenience. It is necessary 
to consider the uncertainties in both basic data and predictions in decid- 
ing on the level of protection required. For storm surge protection, 
these uncertainties include those related to the movement and development 
of the storm, the relation between wind velocity and wind stress, and 
those arising from the uncertainties resulting from approximations and 
assumptions made in the computation of the response of the sea to 
atmospheric stresses. 

These uncertainties will be reviewed both from the standpoint of 
identifying areas in which more basic research is needed and from the 
standpoint of showing how these uncertainties should affect the operation- 
al natural disaster warning service. 



Reprinted from PROCEEDINGS THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2, Oceanography, Toyko 1966 



-49- 

THE DRAG COEFFICIENT BETWEEN WIND AND WATER 

D. Lee Harris. Institute for Oceanography, Environmental Science Services Administra- 
tion, U. S. A. 



Two of the most popular techniques for determining the stress between wind and 
water are to record the slope of a water surface exposed to the wind and to analyze 
the profile of the wind speed above the water according to the Prandtl boundary layer 
theory or some extension of it which allows for the effects of buoyancy when the lapse 
rate is not adiabatic. 

Determinations of the drag coefficient by the first technique are characteristi- 
cally larger than those determined by the second. It will be shown that second order 
phenomena normally overlooked in the application of these techniques act to produce 
an overestimate of the stress coefficients derived by the first technique and to 
produce an underestimate of the stress coefficient derived by the second technique. 



740 



Reprinted from MONTHLY WEATHER REVIEW Vol. 95 No. 11 



Vol. 95, No. 11 



NUMERICAL COMPUTATIONS OF STORM SURGES WITH BOTTOM STRESS 

CHESTER P. JELESNIANSKI 

Institute for Oceanography, ESSA, Silver Spring, Md. 

ABSTRACT 

A linear form of the transport equations of motion is used to compute numerically storm surges generated by 
model tropical storms traveling across model basins. The storms move in any fixed direction and speed relative to 
a straight line coast and have a restricted number of physical parameters to fix their strength and size. These param- 
eters are readily available in most weather stations. 

A dissipating mechanism, introduced by Platzman, using only an eddy viscosity coefficient is modified to include 
a bottom slip current by means of a bottom slip coefficient. These two coefficients are used to control the amplitude 
of resurgences on the sea following the passage of tropical storms. Numerical values for the coefficients are empirically 
determined by comparing computed and observed resurgences off Atlantic City. 

Nomograms prepared from the computations may have some skill in forecasting future storm surges. 



1. INTRODUCTION 

The storm surge prediction problem is concerned with 
I he rise of coastal waters brought about by meteorological 
storms. The rising waters not only inundate coastal areas 
but also act as a pathway for short surface or wind 
waves to move and break farther inland. It is the purpose 
of this paper to provide some further insight into the 
mechanics and prediction of storm surges. 

The response of the sea, from driving forces generated 
by a moving tropical storm, is of such complexity that 
practical results are obtained only through bold assump- 
tions and empirical tests using numerical computations; 
an electronic computer, therefore, is viewed as a laboratory 
to compute storm surges using model storms traveling 
across model basins. The entire response of the sea, 
however, is much too general for storm surge computations 
and only portions of the response are considered. 

In the natural oceans there is a basic flow composed 
of the general circulation, varying seasonally, and the 
daily astronomical tide. The present state of knowledge 
and data acquisition for hurricane conditions on the 
open coast does not permit a direct incorporation of the 
basic flow into the storm surge computations, nor provide 
the ability to consider nonlinear interactions with storms. 
For this reason, and as a great matheinatic convenience, 
only linearized forms of the equations of motion are used 
in the present study. 

The basic flow can be partially accounted for in the 
computations by appending the predicted astronomical 
tide and the observed, extrapolated, or predicted seasonal 
variations of the sea surface to the computed storm surge 
via the superposition principle (Harris [3]). This is feasible 
il the effects of nonlinear interactions are small; in any 
case these corrections can be applied only at shore stations 
where data are available and not in the open sea. 



Model tropical storms have been used by Jelesnianski 
[6] to compute storm surges but without considering 
bottom stress in the storm surge equations of motion. 
The computed surges were found to be reasonable for fast 
moving storms making landfall but had serious deficiencies 
for storms moving slowly or traveling parallel to the coast 
at any speed. Computations therefore were restricted to 
storms traveling at moderate or higher speeds and with 
direction of travel at not too acute a crossing angle to the 
coast. For convenience, storms moving from land to sea 
were omitted even though the computed surges were 
reasonable. 

A detailed description is given in this paper to surges 
generated by storm travel inadmissible in the previous 
paper [6]. These particular surges are complicated in 
space and time. The techniques developed in [6] to predict 
storm surges using a restricted number of meteorological 
parameters are extended to consider storms crossing the 
coast at any angle and speed, as well as storms traveling 
parallel to the coast at any speed and distance from the 
coast. To consider this broad spectrum of storm velocity 
relative to a coast, methods of applying bottom stress in 
the numerical computations are necessary. The methods 
used are useful palliatives in the absence of a sound theory 
for bottom stress and dissipating mechanisms. 

The addition of a bottom stress in the equations of 
motion does not significantly change the results of [6] but 
does have a commanding effect with storm travel inad- 
missible in [6]. Storms traveling parallel to the coast at 
any speed, or landfalling at slow speeds, form second 
order surge oscillations due to initialization effects and 
special wave phenomena, all of significant amplitude; 
these are superimposed on the generated surge and can 
be controlled by a dissipating mechanism. 

Test computations show that certain portions of the 
coastal surge profile are almost unaffected when using any 



November 1967 



Chester P. Jelesnianski 



741 



bottom friction law, including a no-friction law if the storm 
is not moving too slowly. For an observer on sea, facing 
land, and watching a storm landf ailing, the coastal pro- 
file and peak surge to the right of landfall are not greatly 
affected; on the other hand, the profile to the left of land- 
fall is sensitive to the type of bottom stress law used. 

2. EQUATIONS OF MOTION FOR STORM SURGE 
COMPUTATIONS 

The model in this study corresponds to that of the 
previous report [6], except for the addition of bottom 
stress, and consists of an analytically described storm 
traveling across a rectangular shaped, variable depth" 
basin that is open to the sea on three sides. Initially the 
sea in the basin is assumed at rest, and the storm is al- 
lowed to grow to maturity from zero strength in a rapid 
but continuous manner. 

In storm surge computations, we are primarily in- 
terested in the height of the sea surface and only casually 
in the current field. It is convenient then to transform the 
equations of motion to two-dimensional transport fields. 
This transformation, however, presents serious problems 
with bottom stress. 

For future use we shall need a continuity transport 
equation which can be written as (Welander [20]) : 



dh 



where 






a: 



(U, 10= (w, v)dz', i.e., transport components 

ft = storm surge (height of mean sea surface 
above equilibrium level) 
u, v = horizontal components of current field 
7}=depth of the sea 
x, ?y, z' — right hand coordinate system [z' in antic- 
ipation of scaling) . 

The momentum equations of motion (not yet in trans- 
port form) with hydrostatic approximation can be written 
in linear and complex form (Welander [20]) as: 



where 






w=u-\-iv, q- 



-[ 



d 

a( ft-fto) 

dx 



(2) 



+i 



d(ft-fto) ' 



p = vertical kinematic eddy viscosity 
/=Coriolis parameter (constant) 
<y = gravity 

ft =inverse barometer effect (hydrostatic height due 
to surface pressure). 

The last equation considers inertio-gravitational waves 
since the Coriolis parameter is not varied. This was 
purposely done for the storm snree is small compared to 



the scale length of planetary waves. For similar reasons 
a map scale factor is not considered. Lateral stresses are 
excluded since the vertical stress influenced by the surface 
wind is believed to be much larger over most of the area 
of interest. 

To formulate transport fields, one may directly in- 
tegrate (2) in the vertical to obtain 






= Q-iJW+T-T t 



(3) 



wher. 



T s> T b =V 



dw 
ds 7 



complex form of surface, bottom stress 

(4) 



W= complex form for transports 
Q=Dq. 

The surface stress can be formulated as a function of 
the wind, but the bottom stress depends on the vertical 
gradient of the bottom current. Since only transport 
terms are available if (3) is used directly, it has been cus- 
tomary to assume the bottom stress as a simple quadratic 
function of transport in conformity with experiments from 
pipe or channel flow ; corrections to such an empirical law 
for a system under the influence of a surface wind stress 
has been given by Reid [16]. This type of bottom stress 
will not be considered since computational experiments 
gave results that were not always satisfactory. 

Other systems of representing bottom stress, which are 
linear in nature, have been designed by Nomitsu [91, [10], 
[11], [12]; Nomitsu and Takegami [13], [14]; and Platzman 
[15]. Platzman's scheme is more convenient for nu- 
merical computations. In what follows, we will adhere to 
the notation given by Platzman whenever possible. 

Let the surface boundary condition be v(dw/dz')\ z - = o = R, 
where 7? is the complex form of the surface wind stress, 
taken as 



R=^\V. 



W 



where F s = complex wind, p a , p = air, water density, 
C is assumed to be a constant drag coefficient, and 
Cpjp — 3 X 10~ 6 . We formulate the bottom boundary 
condition as 



dw 
b~7 



= SW\-' = - D 



(5) 



where s is a slip coefficient; here we are assuming a 
"gliding" current above a very thin boundary or skin 
layer, where for practical purposes the depth of the skin 
layer is taken as zero. 

If only one friction parameter consisting of an eddy 
viscosity coefficient is used, then computations show that 
the storm surge is somewhat sensitive to small changes of 
the parameter. The introduction of a slip coefficient as a 
second friction parameter greatly reduces this sensitivity 



742 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 



and also gives more freedom when working with dependent 
data to better fit computed and observed surge profiles. 
It is convenient to make the vertical coordinate non- 
dimensional by the transformation z=z'/D. If the time 
derivative in (2) is treated as an operator, and the resulting 
second order differential equation with variable z is solved 
with surface and bottom boundary conditions, then 



i-, sinh az „ . cosh crz , , „ , . 1 n 

wD= R-\ ^-j — (cosh o7f— sw>_iH - 2 V 

r)„v T],a sum a y\ v a 

where 

v>=v/D 2 

''=«=' 0+1) 

a-R+ (sinh a)Q 



(6) 



W_,= 



»[ 



y\ v sinh a-\-y;(j cosh 



'] 



= complex bottom current. 



If (6) is now integrated in the vertical (with respect to 
z from — 1 to 0) , the result is 



where 



7 l ,W J rG{«)]M=QMl + H{a)]R 



(7) 



M= complex transport 

(equivalent to dimensionalized W in (3)) 



G(*y- 



H(<r) = 



[{g}+,coth,-l] 



1- 



sinh a 



m 



+<x coth— 1 



For the purposes of integration with respect to z, and 
of algebraic manipulation, the operators, a, 67(a), a 2 , H(<r), 
etc., can be treated as ordinary algebraic quantities and 
parameters, save that the operator must remain to the 
left of some operand, such as M, Q, or R in equation (7). 

The meaning of a compound operator such as G(u), 
H(<r), etc. is based on power series expansions in a; e.g., 

a(sinh „)F(t) = [c 2 +y+~+ . . . ]F(t) 

(where the terms of the power series are just the same as 
those of a function z sinh z) provided the series converges. 
When it does not converge directly, means similar to 
analytic continuation can be employed to get the result of 
the operator; these means lead to a unique result. 

Equation (7) was formed to set Q by itself; it is just as 
easy to set <j 2 M by itself if this is desired. The choice of 
which term is set by itself can be governed by the nature 
of the numerical scheme to be used. 



Note that for s = 0, G and H are zero; (7) is then no 
more than (3) without bottom stress, i.e., frictionless flow. 
Platzman [15] treated exclusively the special case, s= °o , 
or w-i=0, i.e., no bottom slip. This is equivalent to as- 
suming that the horizontal velocity gradually approaches 
zero. near the bottom. However, the horizontal velocity 
near the bottom is often quite large (excepting a thin 
boundary layer which is not included in the present 
analysis). In order to recognize the existence of this 
boundary layer without being concerned with its detailed 
structure we have taken bottom stress (5) as proportional 
to a slip velocity assumed to glide over the top of the 
bottom boundary layer. Our results with idealized storms 
appear to point out that v controls the peak surge on the 
coast, whereas s controls the dispersion of the surge es- 
pecially to the left of the storm center on the coast. 

The difficulty in applying equation (7) lies in represent- 
ing the operators 67(a) and H(a) numerically. The func- 
tions M, R, and their first derivatives in time can be 
readily approximated directly from available information, 
but higher derivatives resulting from a Taylor's expansion 
of 67(a) and H(a) are more difficult to obtain. 

Accordingly, Platzman suggests that G and H be ap- 
proximated by truncating their Taylor's expansion about 
cr 2 =ifD 2 /p to obtain 

6?(<r)~67 (<ro)+y Qfa) ^ H(a)~H (c )+^ H x {c a ) ^ (8) 

where the subscripts represent the zeroth and first deriv- 
atives with respect to a 2 , and the derivatives are evaluated 
at a 2 =o 2 . Using the approximation (8), equation (7) takes 
on the simpler form 

dM 
bt 

where 



^BQ-ifAM+^C+i^R (9) 



1 + 67, ' 



B 



1 

1 + 67, 



^ 1 + H T 

c== y+g;' j 



GqHi 

1 + 67,' 



Numerical tests using (9) gave good results for slow- 
moving storms, but spurious waves formed, especially 
along the storm's track, with fast -moving storms. When 
the J term was dropped the spurious waves did not occur. 
This situation prompted a closer look at the truncated 
forms of (8) to see whether they are sufficiently represent- 
ative for storm surge computations, and whether the J 
term is important or not. (See Appendix I.) 

Equation (9) with the J term omitted has the real and 
imaginary parts 



W 
dt~ 



dV 
dt r 



■gD 



[* 



d(h-h ) B d(h-h ) 



—B, 



-gD^B t 



dx by J 

d(h—h ) B d(h—h )l 



dy ~ +Bi dx 
-f[ArU-A ( V]+C^r s +0^r s J 



y (io) 



November 1967 



Chester P. Jelesnianski 



743 



DEPTH [FEETI 
83 I66 248 33I 4I4 497 580 662 83 I66 248 33I 4I4 497 580 662 

-I 1 1 1 1 1 1- 




Figtjre 1. — Real and imaginary parts of the four coefficients 
(A, B, C, J) of equations (9) and (17) as functions of Ekman 
number "t" or depth. 

These equations involve only first derivatives with respect 
to time. The six subscripted functions (A, B, C) are 
dependent only on depth when eddy viscosity and bottom 
slip coefficients are specified; their form is given in figure 1 . 

The numerical scheme for (10) used in this study is 
given in Appendix II. An heuristic approach to form 
values for the eddy viscosity coefficient v, and slip 
coefficient s, is given in Appendix III. 

In this study, the parameters describing the model 
storms and basins have a range usually less than an order 
(if magnitude. Thus, in dealing with the drag coefficient 
of the surface wind stress as well as eddy viscosity and 
slip coefficients, we have tacitly assumed constant values 
as sufficiently serviceable for the range of parameters in 
this report. This means that the results of the computa- 
tions are restricted mainly to tropical storms. 

3. GEOGRAPHICAL ORIENTATION, STORM 
PARAMETERS, DEPTH PROFILES, DEFINITIONS 

For purposes of orientation in the following sections, 
the observer will always be at sea and facing the coast, 
The coast to his right will be considered relative north, 
to his left relative south. Crossing angles of the storm's 
path to this orientated coast will be described in me- 
teorological sense; thus a storm on the coast moving from 
relative north lias a crossing angle of 0°, moving normal 
to the coast from sea, a crossing angle of 90°, etc. 

There are five simple parameters to describe the 
strength, size, and motion of a model storm; these in turn 




5 10 15 20 25 30 35 40 45 50 55 60 

RADIUS OF MAX WINDS (MILES) 

Figure 2. — A nomogram relating three model storm parameters, 
stationary storm maximum wind, radius of maximum wind in 
statute miles, and pressure drop. The inflow angle occurs 100 mi. 
from the storm center. The storm center is at latitude 30°. 



determine the driving forces of surge generation, the 
pressure gradient, and wind stress. The parameters are: 

(1) Latitude. — Normally the latitude of the storm's 
landfall; if the storm does not landfall, the latitude of a 
point of interest on the coast, The storm surge is only 
mildly sensitive to this parameter and varies by less than 
10 percent between latitudes 15° and 45°, all other 
parameters being the same. For this reason and because 
we are interested in transient effects as opposed to general 
circulation, latitude is not varied in the equations of 
motion. 

(2) Radius oj Maximum Winds. — The distance from 
the storm center to the maximum wind of the storm. 
This distance is not dependent on storm motion, and for 
any given time it is assumed to be the same in all direc- 
tions. This parameter controls the horizontal extent of 
the surge on the coast. If only the value of the peak surge 
on the coast is desired then the accuracy of this parameter 
becomes unimportant, and for most purposes a rough 
estimate of this distance is sufficient. 

(3) Pressure Drop oj the Storm. — The pressure difference 
from the center to the periphery of the storm. For an 
actual storm, this could be the mean of several differences 
measured along rays from the storm center to the first 
anticyclonically turning isobar. This is the most im- 
portant storm parameter; it controls the peak surge on 
the coast. For a fixed pressure drop, the peak surge on the 
coast is only weakly dependent on the radius of maximum 
wind. The pressure drop is not used directly in the model 
computations, instead it is used as an argument (fig. 2) 



744 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 



to arrive at a more convenient measure for computations, 
the stationary-storm-?naximum-wind. In the previous report 
a simple Newton-Raphson integration method was used 
to derive the nomogram; in this report the more precise 
Runge-Kutta method was used. The differences are only 
minor. 

(4) Speed of Storm. — Rate of motion of the storm center. 
With all other parameters held fixed, there is a critical 
storm speed that gives the highest peak surge on the coast. 

(5) Direction of Storm. — Direction of motion of the storm 
center. With all other parameters held fixed, there is a 
critical direction of storm motion which gives the highest 
peak surge on the coast. 

The computed surge depends on the depth contours of 
the basin as well as the model storm. The continental 
shelf of the oceans vary predominantly in one direction, 
therefore a one-dimensional depth profile is used in the 
model. This profile is used solely for convenience in the 
present stage of developing the dynamic model. There are 
no essential difficulties in the use of two-dimensional 
bottom specifications when such detail is desired or when 
its effect is believed to be significant relative to other 
terms. 

For further reference it is convenient to make the 
following definitions : 

Standard Storm. — A model storm having a stationary- 
storm-maximum-wind of 100 m.p.h. and with storm center 
at latitude 30°. 

Standard Basin. — A model basin having a linear sloping 
depth profile consisting of a 3-ft. drop for each mile length 
along the continental shelf, a 15-ft. depth at the coastal 
boundary, a shelf length of 60 mi., and a deep water open 
boundary depth of 195 ft. This basin has a slightly larger 
slope near the coast than the standard basin of the previ- 
ous report [6] ; hence computed surges from a standard 
storm in this basin are slightly smaller than those in the 
previously used basin. In the numerical model, for a given 
depth profile, the storm surge is only weakly dependent 
on any alteration of the immediate slope at the coast of 
the continental shelf; therefore a vertical wall is substituted 
at the coast with finite depths at the coastal boundary. 

Coastal Surge Profile. — A plot or snapshot picture of the 
surge heights along the coastline for a given time. 

Directly Generated Surge. — Storms traveling parallel to 
the coast can generate traveling and/or standing waves 
superimposed on the coastal surge profile. The first crest 
and trough of the coastal surge profile associated with the 
storm's center, and moving with the storm, is the di- 
rectly generated surge. Figure 3 illustrates the motivation 
for this definition; notice that fast moving storms travel- 
ing parallel to the coast can generate traveling waves 
behind the storm's track and these traveling waves am- 
plify that portion of the directly generated surge behind 
the storm's track, i.e., storms moving to the right amplify 
the directly generated trough, storms moving to the left 
amplify the directl, generated crest. 




Figure 3. — Plots of computed coastal surge profiles generated by a 
storm moving to the right, and moving to the left along the 
coast; and then compared to a stationary storm, center of storm 
remains on coast. 



Resurgences. — At any point on the coast, large ampli- 
tude oscillations of the surge can occur with time for 
storms moving parallel to the coast. These oscillations, 
excluding passage of the directly generated surge, will be 
called resurgences. The resurgences can be shelf seiches 
or edge waves (Munk et al. [8], Reid [17]). Shelf seiches 
also occur for slowly moving storms making landfall; 
this is a special type of resurgence, generally with higher 
harmonics and usually of small amplitude unless the 
storm is moving very slowly. 

4. GROWTH TIME OF STORM, INITIALIZATION, AND 
SPECIAL WAVE PHENOMENA 

The growth time to maturity for fast moving storms 
making landfall, and traveling at not too small a crossing 
angle to the coast, was found empirically to be of trivial 
concern. For storms traveling parallel or nearly parallel 
to the coast at any speed, initialization phenomena de- 
pendent on growth time and of significant amplitude are 
generated or superimposed on the surge profile. 

In order that the peak surge have only weak dependence 
on initial storm placement, it was necessary initially to 
place landf ailing storms at least past the continental 
shelf (the deep water open boundary) or to place storms 
traveling from land to sea at the mirror image point; 
storms traveling parallel or at a small angle to the coast 
required an initial placement based on several criteria 
that will now be discussed. 

Figure 4 shows the directly generated crest plotted against 
time in the case of a stationary, standard storm with center 
on the coast of a standard basin. This peak surge with time 
acts similarly to a damped-forced oscillator. The transient 
oscillations result from rapid growth to maturity of the 
storm; they cannot be completely eliminated for any 



November 1967 



Chester P. Jelesnianski 



745 



reasonable growth time in the computations. Over a 
wide range of growth time the phase varied but the ampli- 
tude of the second crest of the transient oscillations was 
nearly constant. Henceforth, we shall always use 100 min. 
as a growth time solely for convenience. We adopt a 
working criterion that whenever transient oscillations of 
this nature occur, the second crest will be chosen as repre- 
sentative of the peak surge on the coast; the same type 
of transient oscillations will affect the moving directly 
generated surge. Thus for a working criterion, the initial 
placement of the storm center in the model basin must 
be sufficiently distant from the point of interest so that a 
second crest has time to form. 

Figure 4 also shows the surge with time for the point 
on the coast having peak surge in the case of a stationary 
storm placed SO mi. from the coast. Here, there is a 
continuous growth of the surge with time, i.e., it takes 
time for the surge to build on the coast; notice that higher 
harmonic oscillations occur for this case. Henceforth, for 
a working criterion, we shall adopt the computed peak 
surge 8 hr. after initialization as a representative value 
for those cases where the coastal surge displays many 
variations with time. 

The damped-transient oscillations, superimposed on the 
directly generated surge from initialization processes, 
is not the only phenomenon occurring with storms travel- 
ing parallel to the coast. There are also the phenomena of 
standing waves, traveling waves, or a combination of 
both superimposed on the surge profile behind the storm's 
track; there are even further complications if the storm 
is varying in strength, size, and speed with time. 

As an example of these complexities, consider the 
September 1944 storm which moved parallel to the Eastern 
Seaboard (this storm is discussed in Appendix III; its 
track is given in figure 20 and the generated surge at 
Atlantic City in figure 21). Figure 5 pictures the entire 
computed coastal surge profile against time. Notice that 
the traveling directly generated surge associated with the 
storm center has initially a large transient oscillation 
thai dies out with time, and the directly generated surge 
becomes smaller with time due to decreasing storm 
strength with time. In this figure, the oscillations or re- 
surgences witli time at Atlantic City, after passage of the 
directly generated surge, are readily seen to be shelf 
seiches and not traveling edge waves The computed 
resurgences may have been affected by reflective prop- 
erties inherent in the open boundary conditions of the 
model; possibly the use of open boundaries with radiative 
properties would be more appropriate. The two lateral 
(relative north, south) open boundaries, with normal 
transport gradient set to zero, do not strongly affect the 
first few resurgences; this was determined by varying the 
length of (he basin and repositioning the two lateral 
boundaries (in (lie natural coast. No equivalent tests 
were made for the deep water open boundary. 

In t lie numerical model, traveling edge waves will pre- 
dominate over shelf seiches for storms that are fast moving, 




STORM CENTER ON COAST 
STORM CENTER 80 MILES 
SEAWARD 



Figure 4. — The computed height of the peak surge against time 
generated by a stationary storm. 




STORM REACHES 
FULL INTENSITY 

Figure 5. — The computed coastal surge profile, contoured against 
time, for the September 1944 storm modeled in Appendix II. 
The line with arrows represents the position of the storm center 
normal to the coast (center of storm 40 mi. seaward). This figure 
shows the formation of shelf seiches behind the storm's center. 



of constant strength, size, and speed, and for basins which 
have shallower coastal depths and gentler slopes. Consider 
now the above storm but with constant parametric storm 
values equivalent to those observed off Atlantic City; 
consider also a standard basin whose profile differs sig- 
nificantly from that off Atlantic City (fig. 17). Figure 6 
pictures the computed coastal surge profile for this hypo- 
thetical storm and basin. Notice that the resurgences 
which form with time behind the storm's track are now 
traveling waves in contrast to those in figure 5. The 



746 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 



600 



500 -- 



400 -- 



en 



< 
o 
o 



300 -- 



200 -- 



I00-- 








STORM REACHES 
FULL INTENSITY 







H h 

4 8 

HOURS 



12 



Figure 6. — Same as figure 5 for a standard storm, in a standard 
basin, and traveling parallel to the coast at 40 m.p.h. with center 
of the storm 40 mi. seaward. This figure shows formation of 
traveling edge waves on the coast. 



directly generated crest does not change in value, except 
for rapidly decaying initialization phenomena at the be- 
ginning of the computations; the directly generated trough 
is amplified by the traveling edge waves forming behind 
the storm's track. 




Figure 7. — Contours of distance, in statute miles, from landfall 
position to point of peak surge on the coast. Radii are storm 
speeds, rays are crossing angles of storm track to the coast 
(standard storm in standard basin), (a) Radius of maximum 
wind, 15 statute mi. (b) Radius of maximum wind, 30 statute mi. 



For a working convenience, we shall henceforth consider 
only storms of constant strength and size after reaching 
maturity, and traveling with uniform rectilinear velocity. 

5. LANDFALLING STORMS 

Landfalling storms affect only a segment of the coast- 
near the point of landfall ; consequently, we are interested 
not only in the peak surges but also in the horizontal 
extent or dispersion of the surge along the coast. The 
dispersion is strongly dependent on the radius of maximum 
winds. These storms, with speed and crossing angle to the 
coast not too small, do not generate initialization phe- 
nomena and resurgences on the surge profile; therefore the 
generated surge is much less complicated than the exam- 
ples of the previous section. The peak surge occurs at only 
one point on the coast, it is generally larger with storms 
traveling from sea to land. 

As a preliminary aid to determine the surge dispersion 
along the coast, we construct a pre-computed surge pro- 
file generated by a standard storm, with fixed radius of 
maximum winds, moving at fixed velocity across a stand- 
ard basin. In what follows, we assume that the position 
of landfall is known and use it as an origin. To construct 
this preliminary profile, we use nomograms (figs. 7-15) 
which give contours of pre-computed distances and heights 
at selected points along the surge profile. These figures, in 
polar coordinates, have rays as crossing angles of the 
storm to the coast, and radii as storm speed. Figures 
marked (a) and (b) are for storms having 15- and 30-mi. 
radius of maximum winds respectively; presumably one 
can interpolate for other values of the radius. These dia- 
grams consider variation of three storm parameters; in a 
later section we shall consider corrections to the pre- 
computed profile using parameters for any particular 
storm and basin. 

In figures 8 and 9, we have outlined a region in broken 
lines to call attention to edge wave phenomena which can 
affect the directly generated crest and trough respectively. 
An example of this situation is given in figure 3. 



November 1967 



Chester P. Jelesnianski 



747 




Figure 8. — Contours of peak coastal surge values, in feet. Argu- 
ments are identical to figure 7. The upper region bounded by 
broken lines point out edge wave phenomena that could be 
affecting the directly generated crests in the model computations. 



Figure 11. — Same as figure 10, but to left of landfall. 




Figure 12. — Same as figure 10, but for y t peak surge value. 



Figure 9. — Same as figure 8 for the minimum surge, portrayed at 
time of the peak surge. The absolute minimum surge does not 
necessarily occur at time of peak surge. 





Figure 13. — Distance, in statute miles, from peak surge to zero 
surge on the coast. Arguments same as figure 7. 



Figure 10. — Contours of distance on coast, in statute miles, from 
point of peak surge to point on coast having % the peak surge, 
to the right of landfall. Arguments same as figure 7. 



Very slowly moving and landfalling storms form shelf 
seiches with phase angle depending on initial storm 
placement. These seiches are superimposed on the surge; 
thus, for different storm speeds, there is no a priori way 
to relate phase angle of seiches to peak surge on the coast, 
Therefore, it was necessary to force continuity of the 
various contours about the origin of the polar graphs, 



subjectively; the stationary storm at the origin, with 
representative value, was used as an anchor or invariant. 
The surges thus derived never differed by more than one- 
half foot from actual computations. Similar circumstances 
occurred for storms crossing the coast at a small angle 
and at any speed. 

We emphasize that the constructed profile is only for 
the time of peak surge on the coast. The absolute mini- 
mum surge does not necessarily occur at time of peak 
surge; the negative surges on the profile are only transi- 
tory and eventually can turn to respectable positive values 



748 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 




Figure 14. — Distance, in statute miles, from peak surge to minimum 
surge on the coast. Arguments same as figure 7. 








_ 


- 14 
si? 






*"" " 




^^ 




X 






JT-^ 




//■' 




^10 


^O* ^ 


// 


s 






^V ~* -^ 








8_ 

UJ 




/'yC' 






-6 £ 


^V 


s s 










y 








sN. *"" ~- 




^ 




"4 


~~" ~- ^-^-^^^ 


-***'' 






-2 


"""'•-— ^r^ - 


__.- "' LANDWARD 






5EAWARD -~~JJ^ • 










50 7 5 TOO 

| i 1 j 


1 1 

50 25 






25 -" "" _ 










MILES ^-^ __ — -p^~ ~~ 








--2 


/ ^" / 


\^\ 








/ s 








—4 


/ / ' 








-6 


/ <' / 


\ 


\^. 


"V 


/ 


\ 






--IO 


/ 


\ 






■-12 


/ 


\ 






--14 


/ 


\ 






--16 


/ 

. MPH 


\ 








/ rt£l \1f*'t 


\ 






-18/ 


40 MPH 




^ 


— 


—20 


— POSITIVE 

RESURGENCE (40 MPH) 



Figure 15. — Arrival time, in minutes, of peak surge on the coast 
after storm landfall. Arguments same as figure 7. 



Figure 16. — Height nomogram of the directly generated crest and 
trough, and the resurgence amplitude, for storms (standard storm 
and standard basin) moving at different speeds parallel to the 
coast. The abscissa is distance of the storm center from the coast 
in statute miles. 



after passage of the storm. The history of the region of 
negative surges has not been documented. 

The surge profile from a stationary storm can be depicted 
by the nomograms of this section only if the center of the 
storm rests on the coast. If the storm center is at a dis- 
tance from the coast, then the heights of the crest and 
trough can be extracted from figure 16 of the next section 
and the surge profile completed with the nomograms of 
this section. We are assuming here that the dispersion of 
the surge does not depend on distance of the resting 
storm center from the coast; separate computations show 
this to be a good assumption. 

6. STORMS NOT LANDFALUNG 

For convenience, we treat all storm motions that stag- 
nate, loop, recurve, or in any way fail to landfall, as 
storms traveling parallel to the coast. For simplicity, we 
restrict description of the surges from these storms to the 
moving, directly generated surge and follow the rules set 
forth in past sections to form representative surge values. 

We shall not consider here the form* of the coastal 



/option here since the crest and trough 
could he interested in the dispersion on 



•Stationary storms could be treated as an e: 
remain stationary on the coast. In this care oni 
the coast of the stationary surge profile. 

**We do not consider travel along the left side since this is a rare occurrence limited to 
lower California and to the western Floiida coast. 



surge profile at fixed times, nor time of passage of crests 
and troughs on points along the coast. 

To construct a nomogram, for purposes of forecasting 
the directly generated surge from these storms, we con- 
sider a standard storm traveling parallel to the coast of a 
standard basin at particular storm speeds. Let the radius 
of maximum winds be 30 mi.; other values for this storm 
parameter need not be considered since we are primarily 
interested in peak surge and not seiches and resurgences. 
We now focus attention on the directly generated crest 
and trough and note that these are traveling with the 
storm center along the coast. Figure 16 is a resulting 
nomogram from a series of computations which give 
representative values of the directly generated crests and 
troughs for the storm traveling along the right** side of 
the coast at various distances from the coast; above the 
abscissa (miles), positive peak surges are shown, below 
negative peaks. At large distances from the coast, slowly 
moving storms have higher surges (the criteria of the 
previous sections give the surge 8 hr. after initialization; 
hence there is time for the surge to build), but near the 
coast fast moving storms have higher surges. 

The standard basin of this study favors traveling (edge) 
waves as opposed to seiches for fast moving storms moving 
parallel to the coast. One should therefore be careful in 
accepting these resurgences, and the directly generated 



November 1967 



Chester P. Jelesnianski 



749 



trough, as fully representative since we have not con- 
sidered storms that vary in strength, size, and speed, nor 
depths varying in two dimensions, nor curvilinear coasts, 
nor the effect of various depth profiles on the resurgences. 
In the present model these resurgences do not become 
important unless the storm is very fast moving with center 
slightly seaward of the coast. 

Evidence of resurgences (edge waves) does not begin 
until the storm travels in excess of 20 m.p.h., and not until 
the storm travels about 40 m.p.h. is there significant 
amplitude. Figure 16 also shows the amplitude of re- 
surgences for storms traveling at 40 m.p.h. and at time 
10 hr. after initialization; notice that the maximum re- 
surgence amplitude occurs slightly seaward of the coast, 
Greenspan [2]. Only the first resurgence behind the 
storm's track is shown, and this only after passage of the 
directly generated surge since the following resurgences 
are dampened. 

Corrections to the pre-computed surge of figure 16, for 
non-standard storms and basins, are given in the next 
section. 

7. CORRECTING THE PRE-COMPUTED SURGE FOR 
IN-SITU STORMS AND BASINS 

In the development of a practical forecasting system 
for storm surges, it is desirable to modify the preliminary 
constructed profiles and surges of the preceding sections 
for particular storms and basins that differ from standard. 
The corrections would then be for non-standard values of 
stationary-storm-maximum wind, latitude, and basin 
depth profile. 

Correcting the pre-computed surges for different values 
of the parameter, maximum wind, is very easy since the 
computed surge is almost proportional to the square of the 
maximum wind (as shown in [6]). 

For the same pressure drop, the peak surge on the coast 
is not unduly sensitive to the parameter, radius of maxi- 
mum wind. This can be verified with the nomograms of 
figures 2 and 8 and the above correction for the maximum 
wind since the figure is used only to determine peak surges 
on the coast. 

Variations of the latitude parameter alters the computed 
surge in only a minor way (see [6]). It was decided as an 
added convenience to incorporate corrections for latitude 
with corrections for depth profiles. 

Figures 17 and IS give correction factors F D for special 
points along the Eastern Seaboard and Gulf States of the 
United States to correct the precomputed surge for in-situ 
depth profiles; corrections for latitude have been incor- 
porated. Presumably interpolation can be used between 
the special points. The factors were obtained from com- 
putations using the given depth profiles at the special 
points and various storm conditions; they are somewhat 
subjective since they do change with storm conditions, 
but in most cases only slightly. The correction factors 
are for the peak surge and would differ for other points 
on the surge profile, being least reliable for the negative 



portion of the surge. We assume the factor, a function 
of the depth profile normal to the coast, can be used for 
the pre-computed surge profile providing the storms do 
not differ greatly from standard. The factors are not 
invarient when comparing with other varied storm param- 
eters, but they change only slightly for the parametric 
range of storm values used in this study. 

The depth contours of a natural basin vary in two- 
dimensions, but the variation normal to the coast gen- 
erally is much greater than the variation parallel to the 
coast. In this study we compute only for variation of 
depths in one-dimension and assume the depth correction 
factors, applied selectively at selected points along the 
surge profile, are good approximations for two-dimen- 
sional basins. 

The dispersion of the surge on the coast does not change 
appreciably when varying the parameters maximum wind 
and depth profile, but does change some when varying 
the latitude. For convenience it will be assumed here that 
the dispersion of the surge remains invariant. 

There is a unique region along the Florida coast between 
Miami and Palm Beach where the bottom depths descend 
from the coast with extreme rapidity. The model discussed 
here does not cover this case. South of Miami the depths 
descend with equal vigor; however, there is a shallow 
shelf along the coast in this region. It was subjectively 
decided to give this shelf a length of 10 mi. to arrive at 
some correction factor for the non-standard depth profile ; 
the reliability of the factor in this area is questionable. 

To correct the pre-computed surge heights of the 
previous sections for non-standard storms and basins 
along the United States coast, the following could be 
used at selected points on the coast: 

h c =h s (V R /l00) 2 F D 

where h c is the corrected surge height, h s is the standard 
pre-computed surge height, V R is the stationary-storm- 
maximum wind parameter, and F D is the depth profile 
correction factor (figs. 17 and 18). 

8. SUMMARY AND CONCLUSIONS 

It is possible to compute a reasonable storm surge 
tide with a numerical model that uses a simple linearized 
form of the equations of motion. Bottom stress in these 
equations was not found to be significant in surge gener- 
ation with fast moving storms making landfall, but a 
dissipating mechanism was necessary to control large 
amplitude resurgences and/or initialization phenomena 
for storms moving parallel to the coast at any speed, as 
well as slowly moving storms making landfall. 

In this paper, a bottom stress formulation was chosen 
with certain desirable properties in the generation of 
the coastal surge profile. These properties were most 
evident for the range of storm velocity not admissible 
in a previous report [6]. Some of the properties were 
suppression of large transports at and near the coast, 



750 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 




JACKSONVILLE 



Figure 17 '.• — Correction factors at selected points along the Eastern Seaboard of the United States for depth profiles other than standard; 
the factors are used to correct pre-computed surge heights in a standard basin. The inserts are the mean depth profiles of the selected 
points. 



and damping of special wave phenomena and initialization 
effects generated by storms traveling parallel to the coast. 
Since non-dimensional analysis shows that the dissipating 
term is small compared to the inertial term for rapidly 
moving storms traveling across the continental shelf 
(Kajiura [7]), values for the friction parameter were 
chosen so that the coastal surge profile computed with 
or without bottom stress was nearly identical for fast 
moving storms traveling at or near normal incidence to 
the coast. To demonstrate the usefulness of a bottom 
stress formulation with the above properties, observed 



surges generated by a fast moving storm at a tide station 
that was undergoing special wave phenomena and 
initialization effects were compared with computed 
surges. To better fit the observed and computed values, 
the scheme for bottom stress introduced by Platzman 
[15] was modified to include a bottom slip current. 

In [6] a proto-type prediction scheme for forecasting 
storm surges was introduced. This was done with nomo- 
grams that were prepared from pre-computed data using 
the parameters of a standard storm and a standard basin. 
In the prediction scheme, a preliminary surge profile 



November 1967 



Chester P. Jelesnianski 



751 




iS.'o 



Figure 18.' — Same as figure 17 for the Gulf States and Florida. 



was first constructed from the nomograms; three simple 
correction factors for maximum wind, latitude, and basin 
depth profile were then used to correct the preliminary 
profile for in-situ storms and basins that differed from 
standard. In this report the same scheme is adhered to 
except that only two simple correction factors were used; 
for simplification, corrections necessary for latitude and 
basin depth profile were combined as one, at the expense 
of limiting the predicting scheme to the Eastern and Gulf 
States of the United States. 

Our model does not consider curvilinear boundaries, 
bays, inlets, etc. ; consequently the method of constructing 
surge profiles from pre-computed nomograms in this 
study are to be considered only as a preliminary guide 
for field forecasting purposes. 

The important parameters of the storm model are not 
difficult to ascertain or forecast in weather stations 
excepting the point of landfall. For storms crossing the 
coast, the distance from landfall to peak surge is roughly 
equivalent to the radius of maximum winds, and this 
sets the horizontal scale of the entire surge profile; there- 
fore a high order of accuracy in landfall prediction is 
required. 

The methods of this study consider a straight line 
coast. Further research is desirable to consider curvilinear 
boundaries in the model. With this more natural boundary 
condition it should be possible in the future to prepare 



in-situ surge forecasts by computer, using forecasted 
storm parameters and landfall point. The forecasted land- 
fall point would determine the basin to be used as well as 
the depth contours of the basin. 

APPENDIX I 

To test the representativeness of equations (8) and 
(9), we use an heuristic approach (suggested by Dr. A. D. 
Taylor) that only partially resolves the problem. 

Let us consider, for simplicity and illustrative purposes, 
the case of no bottom slip, i.e., s= °° . Then G and H are 



6(a)- 



a 2 tanh a 
a — tanh a 



; H{a)- 



tanh a— a sech a 
a — tanh a 



(ID 



These operators, regarded as analytic functions of <r, 
have removable singularity at a=0, and simple poles 
(i.e., zero denominator) on the imaginary axis of a at 

approximately o-~±i(2n— 1)-. This implies that if (11) 

is expanded in power series about a center in the a plane, 
not on the imaginary axis, the series will converge in 
some region about that center. 

Suppose one of the operands was the function £ r e i <^ <+ * ) 
for some complex values E, /3, cj>. Then 



dt 



2£ e if/K+«) = ^ 3i E e i(0«+*) 



752 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 



so that the effect of operating with d/dt is just the effect 
of multiplying by if3. An operator formed as a "function" 
J (d/dt) has, on the operand Ee'^' + * ) , the effect of multi- 
plying by /(?/?), for the operand Ee'^'+v the operator 
d/dt "takes on the value" i/3. 

In general, the operands will not be of the form £V ! *<0'+*> ; 
however, at any time t for which the operand is not 
zero, there is an exponential function which fits most 
closely to the operand. If the values of E, /3, <j> of the 
approximating exponential do not rapidly change with 
time, tl u it i> reasonable to approximate d/dt with the 
value i|8. 

The values of E, /3, <j> depend on the operands and the 
time t for which the "evaluation of d/dt" is performed 
and are different for the operands M and R. If /3 is real, 
so that the opera nd is neither increasing or decreasing in 
value, the values of G and H will be finite and bounded. 
Figures 19 a-b give the real and imaginary parts of 
G and H against a 2 , with a 2 = iD 2 (j-\-fi)/v (i.e., replacing 



d/dt by i/3) . These figures indicate that a linear approxima- 
tion to G and H may be acceptable, provider ji is not large. 

We first examine our experimental computations 
to determine for which values of /3 the actual oper- 
ands approximate exponentials. (If M=E W+*\ then 
dM/dl=ipM, so 0=(l/iM)dM/dt where Mis i egarded as a 
complex valued function of time and space.) Empirically 
it was noticed that the transport field usually consists of 
a train of vortices along the storm's path; in general, 
these vortices do not travel or increase in strength with any 
great rapidity, suggesting that for the trans] ort operand 
M, the value of /3 remains small, and a linear approxima- 
tion may be acceptable. 

The storm model used in this study is a previously 
determined analytic function, and moves with a uniform 
rectilinear motion. For this case, the time derivative of 
the forcing function can be written in the form 



dt' 



=-v..v 



(12) 





Figure 19. — (a) Plot of real and imaginary parts of G(<r) against 
ia 1 . (b) Plot of real and imaginary parts of H(cr) against ia 1 . 



where V s is the storm velocity. The appearance of V s 
suggests that the value of /3 might be too large to admit a 
linear approximation for H(a), acting on the storm stress 
operand R. This may be why the linear approximation 
of H acting on R in (7) gave spurious waves for fast 
moving storms. 

It appears fioii empirical computations tl at dropping 
the J function in (9) [i.e., H(a)^H (<T )] gave results in 
our numerical computations that could be acceptable for 
the present state of art in storm surge computations. 
We wish to show that this hoMs for the fast moving 
storms through comparisons of computations using an 
exact rather than a linear approximation of H(a). One 
can determine an exact H(a) from the stoi m model itself by 
first forming at any local point: 



R=R e 



i(t-t )(,a-ip) 



(13) 



then using (12); for uniform rectilinear storm motion, 
we have, 

d r =«+^=-i(V s -V)/?. (14) 



dt 

Thus we can then form 



D 2 



R 



[%(f+0)+a]. 



(15) 



H(a), as shown in (11), has poles (zero denominator) and 
cannot be used directly in (7) ; there was no problem with 
poles when only the linear terms derived from the ex- 
pansion of H(a) given by (8) were retained. Instead, we 
first reform (9) and approximate the last term as 



t+ ijdt 



l + H(a) 



G(a)—G)(a ) 



1 + 



(16) 



D 2 /v[c 2 -al] 
If H and G are truncated as in (8) we recapture the left 



November 1967 



Chester P. Jelesnianski 



753 



side. The right side is now free of poles; its value is de- 
termined at each grid point when using (15). Several tests 
were made with (9) where in one case the J function was 
omitt ed and in another case the right side of ( 16) was used ; 
except in a minor sense, there were no significant differ- 
ences in the coastal surge profile with these two cases. 

APPENDIX II 

For numerical computations using finite difference 
forms, the following notation (Shuman [19]) will be 
employed : 

1 2 



— / —ixvy 



u x 



SAs 



-1 





1 


_2 





2 


— 1 





1 



U j.kJ <-' V 



2 4 
1 2 



SAs 



Uf, k ; 



(17) 



U7., 



The following finite difference form was applied to (10) : 
ul = j(A i ) J ,,Ur* 1 -!lD J .d(B r ),,X' /y -(B l ) J ,Ji.r} 



v)=J(A t ) } , k Vfr k 1 -9D J A(B r ) J ,ir+(B i hJ7 V ) 



(18) 



wujri[oyr + orr-2(B.%.B,%)] 



where p is atmospheric pressure and the surface pressure 
gradients are derived from the model storm. There is little 
difference in the numerical results whether the A, B, C 
functions are placed inside or outside the operators 
given in (17) ; (18) is mixed in this respect. 

The closed boundary at the shore was treated by a 
numerical scheme given by Harris and Jelesnianski [4] 
and Jelesnianski [5], when using (18): 



■•-{■ 



Ao m ;= 4#..* h?, k -D 2 . k hl k 



2As f 

(bxA 



f(A r ) . k VS., 



(B r ) 



+ 3(B,) .*Di 



0(B 

'V I z? 

Jilo.k 

Pa \O.s/0,Jt 



To.k 



m,-^- Lm " 



(19) 



The term (dh/dy)™ A . cannot be directly applied since h"' 
is not known on the boundary; tests made showed no 
significant differences in the coastal surge if the term was 
ignored, computed with time value m— 1, or if an iterative 
process was used. 



These forms are an adaptation of a finite difference 
scheme given by Shuman [19]. Note that the time incre- 
ment of the dissipating terms were formulated at time 
(m— 1) rather than time (m). This procedure w - as necessary 
to prevent instability in the finite difference computa- 
tions (Richtmyer [18]). 

The continuity equation (1) becomes 



h 



~TT XVy 

' LJ x 



APPENDIX III 



Observed surge data during storm conditions are of 
poor quality, awkwardly distributed, and too limited in 
quantity to effect a satisfactory comparison between 




Figure 20. — Orienting ;i model basin along a portion of the Eastern 
Seaboard of the United States; the depths chosen for the onc- 
dimensional model basin is shown in the insert, and is the mean 
depths about Atlantic City. The model track, simulating the 
natural storm track, for the September 1944 hurricane, is shown. 



278-472 O - G7 ■ 



754 

8 



MONTHLY WEATHER REVIEW 



Vol.95, No. 11 




H i 

OBSERVED \ I I 

NO BOTTOM STRESS \ 1 1 

NO BOTTOM SLIP, v=25ft 2 /sec /.-■ / 

BOTTOM SLIP; r=.25ftZ/sec; s = 006 ft /sec ^ 



SEPT 1944 HURRICANE 
ATLANTIC CITY 



Figure 21. — Observed and computed surges, against time, at Atlantic City for the September 1944 storm. The basin used in the 

computations is given in figure 20. Hours are for model time. 



observed and computed coastal surge profiles. This 
prevents a direct empirical approach to determine values 
for eddy and slip coefficients. However, the special phe- 
nomenon of observed resurgences at selected tide gages, 
generated by storms traveling parallel to the coast, can 
be used to determine plausible values for these coefficients, 
at least for fast moving storms. 

Since actually observed trains of resurgences are ir- 
regular, we cannot readily obtain these coefficients by 
comparison of computed and observed amplitudes of 
resurgences in sequence. Instead, we shall compare the 
directly generated crest and following resurgences ob- 
served at Atlantic City against computed values; by 
appropriate variations of the slip and eddy coefficients, 
the amplitudes can be made to agree. Comparison of the 
remainder of the surge, observed and computed, against 
time will show whether additional modifications are 
necessary. 

To demonstrate this method consider the path of a 
hurricane shown in figure 20. In this figure a rectangular, 
one-dimensional depth basin is oriented along the coast; 
the depth profile of the basin was derived from a mean 
approximation of the seaward depth off Atlantic City. 
The observed storm varied in strength, size, and speed 
with time (see [1]) ; it had a pressure drop of about 95 
mb. off Cape Hatteras that decreased to about 30 mb. 
off Rhode Island ; its radius of maximum winds decreased 
from 50 to 30 mi.; its speed increased from 25 to 35 m.p.h. 
These model parameters give a stationary storm maximum 




Figure 22. — Comparison of computed surge profiles, without and 
with bottom stress (equation (10)), generated by a fast moving 
storm traveling normal to the coast. The eddy viscosity coeffi- 
cient v ranges through an order of magnitude; no bottom slip. 



wind of about 105 m.p.h. initially and decreasing to 
65 m.p.h. off Rhode Island (fig. 2*). In computations 
described below, the model storm parameters, excepting 
latitude and storm direction, were ohanged at each hour 
of natural time as the storm moved across the basin; after 
passing Rhode Island, the model storm parameters 
remained constant. 

This model storm and basin gave a computed surge, 
with resurgences, at Atlantic City as shown in figure 21 
for various bottom stress conditions. The observed di- 
rectly generated crest was translated to the time origin of 



•The latitude of Atlantic City is used in the computations, consequently the winds are 
slightly different than given in figure 1. 



November 1967 



Chester P. Jelesnianski 



755 




Figure 23. — Same as figure 22 with bottom slip s equal to 0.006 

ft. /sec. 




Figure 24. — Same as figure 21, for hurricane Donna. Eddy and 
slip coefficients were used in the computations. 



the computed crests, i.e., model time. Notice that the 
computed surge without bottom stress has a directly- 
generated crest that agrees with the observed crest but 
the computed resurgences are too large in amplitude; 
this suggests the need of a dissipating mechanism. The 
computed crests at time 4 hr. are the result of initialization 
phenomena due to rapid storm growth to maturity; a 
slower growth would suppress this precursor. 

We wish to determine a value for an eddy viscosity 
coefficient that suppresses the resurgences computed with- 
out bottom stress but at the same time does not affect the 
directly generated crest. To do this we first digress to 
consider the effect of different eddy coefficient values on 
the directly generated surge. We consider at this time the 
case of a zero slip coefficient (no bottom stress) and plot 
the computed surge profile generated by a fast moving 
(30 m.p.h.) standard storm traveling normal to the coast 
in a standard basin (fig. 22). We consider further the case 
of an infinite bottom slip coefficient (no bottom current) 
and bracket the no bottom stress profile in the figure with 
profiles computed with eddy coefficients that range 
through an order of magnitude. The peak surge decreases 
monotonically with increasing eddy values for the range 
shown in the figure. Notice that small values of the eddy 
coefficient give a directly generated crest larger than com- 
putations without bottom stress. We now arbitrarily 
choose a middle value for the eddy coefficient of c=0.25 
ft. 2 /sec. and recompute the surge off Atlantic City. 



For v=.25 ft. 2 /sec, figure 21 shows that the directly 
generated crest is not significantly affected but the re- 
surgences are dampened too strongly; there are also some 
changes in the period of the resurgences. Since the two 
flow conditions, frictionless flow and vanishing bottom 
current, did not adequately portray the resurgences, it 
was decided to use a bottom slip condition to better fit the 
computed and observed resurgences. 

To determine the effects of bottom slip, we return to 
figure 22 and note that the profiles can be thought of as 
extremes ; we then have a certain freedom in choosing the 
bottom slip coefficient between zero and infinity. Figure 
23 illustrates how the profiles computed with stress in 
figure 22 were changed when incorporating a bottom slip 
coefficient of s = 0.006 ft. /sec. The smaller the slip value 
the closer thei profiles approach the no-bottom-stress 
profile. 

Figure 21 shows that when the above values for the 
eddy viscosity and slip coefficients are used the directly 
generated surge is not significantly affected by the bottom 
slip and the agreement between computed and observed 
resurgence amplitude is improved. 

For an independent check of these coefficients, it was 
decided to repeat the computations for another storm, 
hurricane Donna, September 1960. Donna passed Atlantic 
City with its center about 35 mi. seaward. From data 
supplied by the Hydrometeorological Branch of the 
Weather Bureau, ESS A, the storm parameters used in the 
computations were: stationary-storm-maximum-wind 75 
m.p.h. increasing by 0.5 m.p.h. each hour, radius of 
maximum wind constant at 40 mi., speed initially at 30 
m.p.h. and accelerating at 0.667 mi./hr. 2 ; after passing- 
Rhode Island, the storm parameters remained constant. 
Figure 24 illustrates the computed versus observed surge 
with time at Atlantic City. The observed secondary peak 
or spike at time 11% hr. after initialization was not com- 
puted by the model. No explanation is given for this 
observed spike, whether it be dynamically or locally 
generated; it appears to be one of several higher har- 
monics, all of small amplitude, excepting the portrayed 
spike. It should be mentioned that the observed surges 
are best fit-by-eye curves from hourly observations sup- 
plied by the Coast and Geodetic Survey, ESSA; the ob- 
servations were corrected for astronomical tide with the 
methods given by Harris [3]. The computed resurgences 
of both storms in this section are predominantly shelf 
seiches, but there were indications of edge or traveling 
waves but only of small amplitude. 

Although the slip and eddy viscosity coefficient values 
were derived on the basis of fast moving storms passing- 
over a basin equivalent to the seaward depths off Atlantic 
City, we use these same values when computing for 
slowly moving storms, and for all the basins encountered 
on the coastal shelf of the United States. We have done 
this for two reasons: in the first place, storms traveling at 
more than 10 m.p.h. give computed peak surges which 
have only minor differences whether bottom stress is 



756 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 11 



used or not, and in the second place there are only few 
observations of storms traveling less than 10 m.p.li. 
(Harris [3]), and such observations as are available com- 
pare as well with the computed surges of this study as 
those of fast moving storms. 

ACKNOWLEDGMENT 

I am indebted to Dr. A. D. Taylor for his unstinting help and 
assistance in the preparation of this report. In particular I am 
grateful for his suggestions in the preparation of Appendix I where 
he introduced many of the mathematical concepts. 



REFERENCES 



1. H. E. Graham and G. N. Hudson, "Surface Winds Near the 

Center of Hurricanes (and Other Cyclones)," National 
Hurricane Research Project Report No. 39, U.S. Weather 
Bureau, Washington, D.C., Sept. 1960, 200 pp. 

2. H. P. Greenspan, "The Generation of Edge Waves by Moving 

Pressure Distributions," Journal of Fluid Mechanics, vol. 1, 
No. 6, Dec. 1956, pp. 574-592. 

3. D. L. Harris, "Characteristics of the Hurricane Storm Surge," 

Technical Paper No. 48, U.S. Weather Bureau, Washington, 
D.C., 1963, 139 pp. 

4. D. L. Harris and C. P. Jelesnianski, "Some Problems Involved 

in the Numerical Solutions of Tidal Hydraulics Equations," 
Monthly Weather Review, vol. 92, No. 9, Sept. 1964, pp. 
409-422. 

5. C. P. Jelesnianski, "A Numerical Computation of Storm Tides 

by a Tropical Storm Impinging on a Continental Shelf," 
Monthly Weather Review, vol. 93, No. 6, June 1965, pp. 
343-358. 

6. C. P. Jelesnianski, "Numerical Computations of Storm Surges 

Without Bottom Stress," Monthly Weather Review, vol. 94, 
No. 6, June 1966, pp. 379-394. 

7. K. Kajiura, "A Theoretical and Empirical Study of Storm 

Induced Water Level Anomalies," Project 202, Reference 
59-23F, Texas A. & M. University, Department of Ocean- 
ography and Meteorology, Dec. 1956, 97 pp. 

8. W. Munk, F. Snodgrcss, and G. Carrier, "Edge Waves on a 

Continental Shelf," Science, vol. 123, No. 3187, Jan. 1956, 
pp. 127-132. 



9. T. Nomitsu, "A Theory of the Rising Stage of Drift Current 
in the Ocean: I. The Case of No Bottom Current," Memoirs, 
College of Science, Kyoto Imperial University (Series A), 
vol. 16, 1933, pp. 161-175. 

10. T. Nomitsu, "A Theory of the Rising Stage of Drift Current 

in the Ocean: III. The Case of a Finite Bottom-Friction 
Depending on the Slip Velocity," Memoirs, College of Science, 
Kyoto Imperial University (Series A), vol. 16, 1933, pp. 
309-331. 

11. T. Nomitsu, "On the Development of the Slope Current and 

the Barometric Current in the Ocean: I. The Case of No 
Bottom-Current," Memoirs, College of Science, Kyoto Im- 
perial University (Series A), vol. 16, 1933, pp. 203-241. 

12. T. Nomitsu, "Coast Effect Upon the Ocean Current and the 

Sea Level: II. Changing State," Memoirs, College of Science, 
Kyoto Imperial University (Series A), vol. 16, 1934, pp. 
249-280. 

13. T. Nomitsu and T. Takegami, "On the Development of the 

Slope Current and the Barometric Current in the Ocean: 
II. Different Bottom Conditions Assumed," Memoirs, College 
of Science, Kyoto Imperial University (Series A), vol. 16, 
1933, pp. 333-351. 

14. T. Nomitsu and T. Takegami, "Coast Effect Upon the Ocean 

Current and the Sea Level: I. Steady State," Memoirs, 
College of Science, Kyoto Imperial University (Series A), 
vol. 16, 1934, pp. 93-141. 

15. G. W. Platzman, "The Dynamical Prediction of Wind Tides 

on Lake Erie," Meteorological Monographs, vol. 4, No. 26, 
Sept. 1963, 44 pp. 

16. R. O. Reid, "Modification of the Quadratic Bottom-Stress Law 

for Turbulent Channel Flow in the Presence of Surface Wind 
Stress," Technical Memorandum. 93, U.S. Army Corps of 
Engineers, Beach Erosion Board, 1957, 33 pp. 

17. R. O. Reid, "Effect of Coriolis Force on Edge Waves (1) 

Investigation of Normal Modes," Journal of Marine Research, 
vol. 16, No. 2, 1958, pp. 109-144. 

18. R. D. Richtmycr, Difference Methods for Initial-Value Problems, 

Interscience Publishers, New York, 1957, 238 pp. (see p. 94). 

19. F. Shuman, "Numerical Experiments with the Primitive Equa- 

tions." The Proceedings of the International Symposium on 
Numerical Weather Predictions, Tokyo, .Nov. 7-13, 1060, 
Meteorological Society of Japan, Tokyo, Mar. 1962, pp. 85- 
108. 

20. P. Wclander, "Numerical Prediction of Storm Surges," Ad- 

vances in Geophysics, vol. 8, Academic Press, New York, 
1961, pp. 315-379. 



[Received January 30, 1067 ; revised July 26, 1967} 



Ausust 1967 



Reprinted from MONTHLY WEATHER REVIEW Vol. 95, No. 8 



565 



ATMOSPHERIC WATER VAPOR PROFILES DERIVED FROM 
REMOTE-SENSING RADIOMETER MEASUREMENTS 

PETER M. KUHN 

Atmospheric Physics and Chemistry Laboratory, Institute for Atmospheric Sciences, ESSA, Madison, Wis. 

JAMES D. McFADDEN 

Sea Air Interaction Laboratory, Institute for Oceanography, ESSA, Silver Spring, Md. 



ABSTRACT 

The feasibility and preliminary testing of a low cost, remote-sensing air-borne, double bolometer technique for 
inferring atmospheric water vapor is illustrated. To deduce the water vapor profile with commercially available equip- 
ment, the radiative transfer equation is solved for the water vapor transmissivity employing an input data remote 
radiometer-measured upward irradiances obtained at aircraft holding levels. Radiometers sensitive in two separate 
spectral bands are used. The primary radiometer covers the 4.39, to 20.83^. broad atmospheric radiation band, and 
the second, for surface temperature deduction, covers the atmospheric window region, 7.35 to 13.16^. 

The transfer solution results are acquired from computer programs developed specifically for this purpose. 
Results indicate an accuracy for inferred total troposphcric water vapor and mixing ratio profiles close to that of the 
standard sounding electrical hygrometer. The absolute accuracy of the radiosonde hygrometer, considering surface 
calibration procedures, and for a single ascent, is not better than ± 12 percent. The absolute accuracy is greatest 
for "dry" soundings where the largest changes in irradiance occur for given changes in moisture. 

Specifically, tests for a vertical profile averaging 6.00 gm./kg. of water vapor produce an average error of 0.70 
gm./kg. in the inferred mixing ratio. The average error in mixing ratio obtained by this technique for profiles aver- 
aging 2.3 gm./kg. is 0.05 gm./kg. The implications for use on high-flying aircraft or on rockets with highly sensitive 
radiometers are obvious. The primary purpose in reporting this research is to suggest a technique and illustrate its 
use. It is clear that with more sensitive bolometer radiometers with selective band pass filters a considerable increase 
in accuracy can be achieved. 



LIST OF SYMBOLS 

Upward irradiance (watts/meter 2 ) 

Subscripts employed in indexing variables 

Wave number increment (centimeter -1 ) 

Black body irradiance (watts/meter 2 ) 

Wave number (centimeter -1 ) 

Temperature (°C.) 

Pressure (millibars) 

Filter transmissivity (percent) 

Transmissivity increment (percent) 

Water vapor quantity 

Carbon dioxide quantity 

Subscript denotes surface value of subscripted 

parameter 

Mixing ratio (grams/kilogram) 

Exponent of a power law equation 

Optical depth of atmospheric gas (grams/ 

centimeter 2 ), pressure and temperature scaled 

Calculated upward irradiance (watts/meter 2 ) 

Subscript denoting irradiance 

Generalized absorption coefficient for water 

vapor after Elsasser [9] 

Limiting wave number increment identifier 



n Number of atmospheric levels between surface. 

and a reference level 
T eQ Black body equivalent radiating temperature 

r Transmissivity (percent) 

1. INTRODUCTION 

The radiative power transfer equation can be solved 
iteratively to infer atmospheric water vapor from remote 
radiant power measurements. The purpose of this research 
is to propose and describe this technique for deducing 
water vapor quantities employing observations of radiant 
power as input to the radiative power transfer equation. 
With more sensitive bolometer radiometers having selec- 
tive band pass filters greater accuracy than is reported 
can be obtained. On-hand equipment was used in this 
pilot study. 

The observations were made in two spectral regions, 
4.39 through 20.83u and 7.35 through 13.16/u. Results of a 
similar technique employing balloons were given by 
Kuhn [1] and Kuhn and Cox [2]. The technique differs from 
those of satellite radiometric inferences of atmospheric 
water vapor and temperature (Houghton [3] ; Wark [4] ; 
Moller [5]; King [6], [7]). The latter observations are 



566 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 8 



necessarily limited to observations from a fixed satellite 
orbit. They employ highly sensitive sensors receptive to 
radiant power in one or more different spectral intervals. 
This procedure requires measurements of temperature, 
height, and spectral irradiance at a number of aircraft 
holding levels. Two "shelf-type" radiometers sensitive 
over two different spectral intervals constitute the sensor 
capability. One radiometer monitors the air-surface 
interface temperature in the relatively transparent posi- 
tion of the atmospheric spectrum, while the other measures 
the spectral component of upward terrestrial long-wave 
irradiance as a function of height in the broad-band, 
earth-atmosphere, self-emission region. Ideally, this second 
radiometer would be sensitive over the strongly absorbing 
atmospheric water vapor band centered at 6.7/x. Funding 
and ready availability prevented use of such a special 
purpose bolometer radiometer. 

2. RADIANT POWER COMPUTATIONS 

As mentioned, pressure, temperature, and water vapor 
data are the normal input to the radiative transfer equation 
solution for spectral irradiance passing upward through the 
atmosphere. 

For a plane parallel atmosphere, containing no scat- 
terers, in local thermodynamic equilibrium and consisting 
of gaseous water vapor and carbon dioxide, the upward 
irradiance through any reference level above the surface 
may be obtained by the following finite difference form of 
the radiative transfer equation, 

m n 

Ft =-EAv,E5^, T(p))$(v)AT t (v, u*(p, w), T) 

m n 

-S>,S-B*(", T(p))*( v )A Tt ( v , u*(p, C), T) 

;=1 i=\ 

m 

IS^, T(p ))(r t (v, U*(p, w), T)rt{v, u*(p, C), T.) (1) 

i = l 

The effects of other radiatively active gases such as ozone 
and nitrous oxide in the wavelength regions considered are 
insignificant, amounting to less than 1 percent of the 
upward irradiance, and are not considered. 

Equation (1) is employed in deducing the quantity of 
atmospheric water vapor from measurements of upward 
irradiance for a particular spectral interval. An iteration 
procedure resulting in a direct solution of the water vapor 
transmissivity, t w {v, p, T), is used. Since the water vapor 
transmissivity is a function of the quantity of water vapor, 
w, beneath a given reference level, and since the amount of 
water vapor is a function of the mixing ratio, the solution 
yields the mixing ratio. 

The iteration procedure requires calculations of irradi- 
ance with a stepped series of trial values of water vapor 
(equation (1)) until the difference between calculated and 
observed upward irradiance is minimized. Carbon dioxide 
emission and transmission are calculated assuming a 
constant mixing ratio. A first approximation for the water 



vapor profile is described by a power law expression of the 
form, 

w=w a {pi Po y (2) 

after Smith [8]. X, the exponent of a power law expression, 
changes the water vapor profile as required in the iteration. 
For tropical soundings W is assumed to be 5.0 gm./kg., 
certainly a lower bound. For mid-latitude summer sound- 
ings, W is assumed to 0.6 gm./kg. For mid-latitude 
winter soundings W is assumed to be 0.06 gm./kg. In 
other words, a lower bound is chosen to start the compu- 
tations. 

The iteration procedure, involving repeated solutions of 
equation (1), requires minimizing the quantity, 

i 

Stepwise changes in X, (equation (2)) for subsequent 
successive increases in W Q provide the repeated input of 
the "trial" water vapor quantities required for equation 
(1). The computer evaluates F t ] from an initial "mini- 
mum" profile of W shaped by an initial X value of 0.5. 
The X values are stepped upward to a maximum value of 
3.0 and then the process repeats with a new stepped 
increase in W . Negative values of X will allow the mixing 
ratio profile to increase with altitude above the surface. 
The changing of the entire water vapor profile by the 
power function approximation of equation (2) imposes a 
stabilizing constraint on the solution of equation (1). This 
same procedure has been used by Kuhn and Cox [2] to 
infer stratospheric water vapor profiles. It should be noted 
that the constraint of equation (2) does not preclude 
convergence at every level, within reason, since the step- 
wise variation of X allows, literally, almost any charac- 
teristic shape to the W profile to obtain. Average computer 
solution time is 0.3 min. (CDC-1604) for 10 levels, over 
the spectral range 4.39 to 20.83ju (480-2280 cm.-'). 

3. UNIQUENESS OF THE SOLUTION FOR INFERRED 
WATER VAPOR 

In view of the rate of change of the water vapor slab 
transmissivity, r F , with changes in the amount of atmos- 
pheric water vapor, u*, it is necessary to establish the 
uniqueness of the radiometrically inferred water vapor 
quantity. Figure 1 gives the water vapor slab or irradiance 
transmissivity as a function of the sum of the logarithm 
of «*, the pressure and temperature scaled optical thick- 
ness, and the logarithm of the generalized absorption 
coefficient L, (Elsasser [9]). This is expressed by, 



tv=t f (logio «*+logio L). 



(3) 



From this figure it is evident that the greatest change in 
transmissivity for a given change in log u*-\-log L occurs 
between values of —1.50 and 0.50 for log u*+\og L. 
Assuming a mean value for log L of —0.50, this represents 



August 1967 



Peter M. Kuhn and James D. McFadden 



567 




WAVENUMBER (CM"') 



-2 -I 
LOG U + LOG L 



Figure 1. — Water vapor beam transmissivity vs. (logi M* + logioi). 



an optical thickness range of from approximately 0.1 
gm./cm. 2 to 10.0 gm./cm. 2 

Aerosol contamination is clearly evident as a sharp 
discontinuity in the observed moisture profile. In fact, 
detection of thin clouds at night is possible with these 
instruments. 

4. IRRADIANCE OBSERVATIONS 

The primary instrument employed in this research was 
a chopper bolometer radiometer having a 30° optical 
field of view, germanium optical flat-front lens with a 
spectral bandpass from 4.39 to 20.83ju (480 to 2280 cm. -1 ). 
The mean band transmissivity is 0.50. 

The relative resolution and special characteristics of 
the primary radiometer used in these experiments are 
given in table 1. Various optical companies can provide 
bolometer radiometers with resolution of at least 0.025°C, 
twice the resolution of the unit used. Thus for a 0.025°C. 
change in target temperature at 5.0°C the corresponding 



Table 1. — Radiometer specifications 



Spectral passband 

Average filter transmissivity 

Field of view 

Maximum temperature resolution 

Irradiance change behind germanium flat filter 
for 0.05'C. change at 5.0°C. 

Temperature range 

Recorder output.. 



4.39 to 20.83 ». 

0.58 

30°. 

0.05°C. 

0.7 micro watt/cm.' (.007 watt/m.') 

-40.0°C. to + 30.0°C. 

0-50 millivolts full scale into 1000 ohms 



00 


1500 


14 13 


12 


1 IOOO . 


300 


800 






700 






, , , |, | 




' 








' 






O 10 gm/cm 2 THRU 2000" 














80 




V j 






















o 




















60 




, 




















X 






















o , 
i 1 gm/cm 2 THRU 3000 














40 




















!tf 






|\ 










20 




•iily^i! 






\ 












Jpi^ 








V --x, 


,x> 








v///////i 


'/M&Ss*o. 




~*« 









8 9 10 II 12 13 

WAVELENGTH (MICRONS) 

IRW-FILTER TRANSMISSIVITY 



Figure 2. — Window radiometer filter transmissivity vs. wavelength. 



2500 



WAVE NUMBER (CM"') 
1000 625 



500 




•- 4 6 8 10 12 14 16 18 20 

WAVELENGTH (MICRONS) 

Figure 3. — Broad-band radiometer filter transmissivity vs. wave- 
length. \og 10 L vs. wavelength. 



irradiance change behind the optical flat filter is 0.0035 
watt/m. 2 For an average tropospheric sounding to 20,000 
ft., this would correspond to a mean water vapor mixing 
ratio resolution of 0.05 gm./kg. or 50 parts per million 
for a moderately dry atmosphere. Throughout, we are 
considering air-borne radiometers at costs not exceeding 
$10,000. The absolute accuracy of the broad bandpass 
radiometer is 0.028 watt/m. 2 The absolute accuracy of 
the "window" radiometer is 2°C. above 0°C. 

The curves of the filter transmissivity of the "window" 
radiometer and the primary broad-band earth and atmos- 
phere self emission radiometer are shown in figures 2 
and 3. The solid angle aperture of the surface temperature 
monitor "window" radiometer is 3°. The radiometers 
were calibrated against a hemispherically symmetrical 
black source. We then have, 



F\?=^ B(v, 



T t Mv)dv. 



(4) 



The equivalent blackbody temperature T eq , can be 
determined from equation (4). B(v,T eq ) is the hemisphere 
blackbody irradiance. The curves of radiometer power 
versus equivalent blackbody source temperature are 



568 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 8 



10 

5 



_ -5 
o 

V 10 

-15 
-20 

















! • ' 






















































































.•' 










CALIBRATION 














7.35 - 


3 16 u 





1.6 1.8 2.0 2.2 2.4 2.6 2.8 
(MICRO WATTS/CENTIMETER 
BAND IRRADIANCE 



30 
2* 



3.2 



Window radiometer calibration curve, equivalent 
temperature vs. micro watts/square centimeter. 



CALIBRATION 

30' FIELD OF VIEW 



Figure 4.— 
blackbody 



6.0 7.0 8.0 9.0 10.0 

SPECTRAL IRRADIANCE (WATTS/METER 2 ) 

Figure 5. — Broad-band radiometer calibration curve, equivalent 
blackbody temperature vs. watts/square meter. 



reproduced in figures 4 and 5 for the window and broad 
bandpass radiometers, respectively. 

Reference to figure 2 shows the considerable oveilap of 
the water vapor absorption band in the bandpass area, 
7.1 to 9.5m- To show the closing effects of this band, ir- 
radiance calculations for received power were run for the 
June mean monthly sounding at Saidt Ste. Marie, Mich., 
from sea level to 18,000 ft. Figure 6 illustrates the influ- 
ence of water vapor absorption for this sounding in the 
shorter-wave end of the filter used on the window radiom- 
eter (7.35-13. 16/u), and the lesser influence in the 10.00 
to 12.05-/. bandpass of a curiently available "window" 
radiometer. The deduced surface temperature error for 
the narrow pass filter is about half that of the window 
radiometer used in this experiment when observing the 
surface at 700 mb. (or 10,000 ft.). In addition, a tempera- 
ture and moisture inversion below 900 mb. has consider- 
ably less effect in the narrower bandpass region. These 
facts are, of course, not new, but in light of the fact that 



500 - 



600 - 



700 - 





SSM 


JUNE 


© © 


10.00 


12.05 MIC 


"" 






1 

\ 

® TARGET 




- 






» TEMP. 

1 © T 
\ \ 










\ \ 

© © 












\ \ 












s © 

\ \ 
\ \ 

© © 














©<? 






1 


l 


i \ 

3 © 
1 J 

1 o 1 


i 



o- 800 - 



900 - 



1000 

7 8 9 10 11 

TEMPERATURE °C 

Figure 6. — Temperature correction vs. pressure at Sault Ste. 
Marie, Mich. (June) for radiometers equipped with 7.35-13.16-m 
filter and a 10.00-12.05-m filter. 



IR radiometers are in such heavy use today in a variety 
of disciplines, this point deserves this amplification. 

5. AIRCRAFT SOUNDINGS 

The NCAR Queenaire Beechcraft was made available 
for this research by Dr. D. R. Rex, Director of Flight 
Facilities at National Center for Atmospheric Research. 
Viewing ports with shock mountings supported the two 
radiometers. Simultaneous measurements of the two up- 
ward irradiances, altitude, and air temperature were made 
coincidentally with visual observations of the surface. 

One aircraft sounding was made in visually determined 
cloudless conditions on July 14, 1965. The area surveyed 
was over Lake Superior, 20 mi. east of Duluth, Minn., 
covering the period 2245 cdt through 2331 cdt. Table 2 
gives the observed pressure, air temperature, surface 
temperature, mixing ratio, and upward flux. In addition it 
displays the calculations of upward irradiance and the in- 
ferred mixing ratio vertical profile. The iteration on 
mixing ratio converges quite rapidly. 

Table 3 gives the results of a second ascent made in a 
light aircraft, to approximately 9,000 ft., on May 25, 1966, 
just east of Green Bay, Wis., but not over Lake Michigan. 
The atmosphere was fairly moist, with an optical thickness 
of 2.1 gm./cm. 2 through 10,000 ft. 

The several tabulations presented enable a comparison 
of measured and calculated irradiances and the inferred 
water vapor profile in gm./kg. The errors, shown in the 
last column, are small enough to make these remotely 
sensed inferred water vapor measurements useful. 



September 1967 



Reprinted from MONTHLY WEATHER REVIEW Vol. 95, No. 9 



627 



THERMALLY AND FRICTIONALLY PRODUCED WIND SHEAR IN THE PLANETARY 
BOUNDARY LAYER AT LITTLE AMERICA, ANTARCTICA 

BERNHARD LETTAU 

Institute for Atmospheric Sciences, ESSA, Silver Spring, Md. 

ABSTRACT 

Pilot balloon wind profiles obtained by the first and second Byrd Antarctic Expeditions arc analyzed to show 
that the mean observed wind shear between the surface and 1,000 m. can be resolved into a frictional component 
which produces a normal boundary layer wind spiral, and a thermal component resulting from the temperature 
gradient at the ice edge, which deforms the normal wind spiral. Values of surface stress, surface Rossby number, gco- 
strophic drag coefficient, energy dissipation, and roughness length derived from the wind profiles are collectively 
sufficiently different from values obtained over land or water surfaces, to suggest that the ice surface produces its 
own characteristic wind distribution. 



1. INTRODUCTION 

Little America Station was first established by the 
Byrd Antarctic Expedition at 78°34' S., 163°56' W., near 
the seaward edge of the Ross Ice Shelf in January 1929, 
and continuous meteorological measurements were ob- 
tained through February 1930. The base was reoccupied 
in March 1934 by the Second Byrd Antarctic Expedition 
and finally dismantled in February 1935 after another 
full year. Included in the data were 983 pilot balloon 
wind profiles— 414 in 1929-30, and 569 in 1934-35— from 
which wind speeds and directions for standard levels at 
roughly 200-m. intervals have been tabulated and pub- 
lished (Grimminger and Haines [2]). In April 1940, the 
West Base of the United States Antarctic Service Expedi- 
tion was established as Little America III, 7 mi. north- 
northeast of the camp of the Byrd expeditions. This sta- 
tion was operated until January 1941, and produced an 
additional 233 wind profiles, which, however, have not 
been used here. 

In this preliminary study the individual mean wind 
shears between the surface and the top of the boundary 
layer have been separated into thermally and frictionally 
produced components, which are classified by season and 
by surface wind direction. Representative mean wind 
profiles are analyzed for various surface parameters in a 
later section. 

2. WIND DATA 

Within the planetary boundary layer of a barotropic 
atmosphere the wind profile is a function of the surface 
stress, the Coriolis parameter, and the horizontal pressure 
gradient. The resulting hodograph has a spiral form with 
the surface wind directed to the left of the free ah geo- 



strophic wind in the Northern Hemisphere, and approach- 
ing it asymptotically at the top of the boundary layer. 
In the Southern Hemisphere the surface wind is to the 
right of the geostrophic wind. 

In the following discussion a Cartesian coordinate 
system will be used whose components are directed parallel 
and normal to the surface wind. Components along and 
to the right of the surface wind will be defined as positive. 
In this system, applied in the Southern Hemisphere, the 
wind vector at the top of the planetary boundary layer 
(H= 1,000 m.) will generally have a positive parallel and 
a negative normal component. 

The condition of barotropy is rarely fulfilled in the 
boundary layer, particularly not at Little America where 
the seaward edge of the Ross Ice Shelf provides a strong- 
horizontal temperature contrast throughout the year. The 
relatively warm water to the north and the colder ice to 
the south produce a thermal wind parallel to the ice edge, 
generally toward the east, which will distort the simple 
spiral hodographs. Under the given geographical condi- 
tions the spiral will be elongated for westerly winds and 
foreshortened for east winds. 

In preparation for the analysis, the surface and 1,000-m. 
wind readings were extracted from the pilot balloon 
observations at Little America for both the 1929-30 and 
1934-35 seasons, and were grouped by surface wind 
direction and by season. The directional resolution was to 
16 points, while the seasonal distribution was limited to 
summer (November to February), and winter (May to 
August). The directional distribution is asymmetric with 
a preponderance of observations of southerly winds at 
the surface. The least frequent wind direction was north- 
northwest with two cases, both occurring in summer; 



628 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 9 



the maximum number in each season was 47, for east 
winds in summer, and south-southwest winds in winter. 
It should be remembered, however, that, northwesterly 
onshore winds were generally accompanied by low cloud 
or fog, and that consequently the asymmetry is accentu- 
ated, if not caused entirely, by the lack of a 1,000-m. 
value. It is also true that when drifting snow or low clouds 
precluded a reasonably complete sounding the balloon 
launching schedule was suspended temporarily. 

For each sounding that extended above a nominal 
altitude of 1,000 m. (tabulated as an actual 990 in.) the 
components of the 1,000-m. wind parallel and normal to 
the surface wind were obtained. The component values 
were then averaged by class, and the total shear, i.e., the 
differences between components at 1,000 m. and the sur- 
face, were calculated. The averaged values are given in 
table 1 by surface wind direction and season. 

The directional distribution of the surface wind speeds 
shows that in summer easterly winds are somewhat 
stronger than westerly winds, while in winter, winds 
with a component from the northeast are stronger than 
winds with a component from the southwest. If the mean 
wind speed from each direction is considered representa- 
tive of that sector, the mean summer and winter wind 
speeds are nearly the same at about 4 m.p.s. 

The directional distribution of the mean shear com- 
ponents shows that the parallel component of the 1,000-m. 
wind is less than the surface speed for easterly wind 
directions, and exceeds the surface speed for westerly 
wind directions in both winter and summer. This would 
be expected from regional horizontal density gradients 
and from the station location with respect to the open sea. 
The normal component of the shear vector is directed to 
the left for all surface wind directions in all seasons, 
however, its magnitude is greatest for winds generally 
from the north, and least for southerly winds. The angular 
deviation of the 1,000-m. wind to the left of the surface 
wind, when averaged over all wind directions, is 24° in 
summer and 28° in winter. 




Figure 1. — Geometric constructions to determine the frictional 
and thermally produced shear vectors. V and AV are the surface 
wind vectors and observed shear vectors, aV|l, and aV 2 f arc the 
frictionally produced wind shear vectors, and T is the thermal 
wind vector. Sec text for details of construction. 

3. METHOD OF ANALYSIS 

A single shear vector, which may represent the sum of 
the frictionally and thermally produced shear, may not 
uniquely be resolved into these two elements. It becomes 
necessary to take at least pairs of observed shear vectors 
and to make some assumptions about the structure of the 
wind profile within the boundary layer. Suitable assump- 
tions are: that for each pair the thermal wind vector 
stays the same, that the angles formed by the frictional 
shear vectors and the surface wind are equal, and that the 
magnitude of the frictional shear vector is proportional 
to the surface wind speed. These assumptions correspond 
to a fixed geographic orientation of the thermal wind 
vector, and a fixed orientation of the frictional shear 
vector with respect to the surface wind direction; con- 
sequently, any angular difference between two surface 
wind vectors will be sufficient to determine uniquely 
the thermal and frictional shear vectors. 






Table 1. — Averaged surface wind, and component values of (he observed wind shear between the surface and 1,000 m. by surface wind direction 
and season. Surface wind speed units are meters per second; shear units arc meters per second per kilometer. 



SUMSIKlt 

Surface wind 

Shear component 

parallel... 

normal. . . 

WINTER 
Surface wind. . 
Shear component 

parallel. . .__ . 

normal 



(I. 71) 
-3.48 



0.70 
-2. 90 



0.34 
-3.08 



3.48 
-0.51 



-0.01 
-2.50 



4.40 

-2.82 
-1.12 

3.17 

-0. 00 
-1.74 



Surface Wind Direction 



-2.80 
-1.43 



-0.03 
-1.73 



-2.29 
-1.37 



-0. 11 
-1.14 



-1.30 
-1.78 



0.70 
-1.04 



-1.40 
-1.29 



0.54 
-1. 15 



1.03 
-1.83 



0.99 
-1.05 



2. 71 
-2.02 



1.47 
-1.79 



3.01 
-2. 50 



2.94 
-1.39 



4. 11 
-2.51 



w 


WNW 


NW 


NNW 


2. 89 


2.72 


3.34 


4.09 


3.79 
-1.81 


4.09 
-3.37 


4.27 
-3. 49 


2.01 
-3.50 


2.58 


2. 73 


3. 13 


5. 52 


4. 31 

-■>. 50 


2. 93 
-4.80 


1.87 
-6.00 


0.72 
-4.03 



September 1967 



Bernhard Lettau 



629 





NORTH ^ \ ) \ \ 

^\ \ / \ 






">^>\ \ \ 








/ ^~\^ 








Y- J s — 








L -'-^""/-' 


\ \ ^-^" 






\ s-\ / 


\ ^\ 


--- 




Wind Seed Imps) ^-^ 


s. X s 







12 3 4 5 x 
Wind Sh.or (mp5/km) 





Figure 2. — Directional distribution of the surface wind vectors, 
frictionally produced shear vectors, and thermal wind vectors. 
Summer. 



\ \ 


, 


NORTH 1 


/ 


1 k 


\ 


\ 

\ f" 

/ / 




y 4 






(y 




V— --"~ ' 


\ ^~ 
\ 

\ / 

w.nd Speed Imps) ^ I 

12 3 4 5 -yj' 
Wind Sheer Imps /km) 


~~~~~'—-.. ^ 



Figuke 3. — Directional distribution of the surface wind vectors 
frictionally produced shear vectors, and thermal wind vectors. 
Winter. 



The separation of the two shear vectors is most straight- 
forward if opposed wind directions are paired, as is shown 
in the example in figure 1. Vectors of surface wind and 
observed shear are drawn so that the heads of the observed 
shear vectors coincide. In this hypothetical Southern 
Hemisphere case, the east wind V I; turns sharply to the 
left, while the west wind V 2 , turns slowly to the right 
with altitude. 



The following will explain the method in more detail. 
Since the thermal wind vector is assumed to be the same 
in both observations, and since the observed shear vectors 
were drawn to one point, we may allow the head of the 
thermal wind vector to fall on that point. It then follows 
that the heads of the frictional shear vectors for the two 
surface winds must also fall on one point, which must be 
the tail of the thermal wind vector. The second assump- 
tion, that the angles between the surface winds and the 
frictional shear vectors are the same, requires that this 
triple point lie on the line joining the heads of the two 
surface wind vectors. The third assumption, that the 
magnitude of each frictional shear vector is proportional 
to the corresponding surface wind, requires that this 
point coincide with the intersection of the lines joining 
the heads and the tails of the two surface wind vectors. 
In this example the frictional shear vector displaces the 
1,000-m. wind vector 16° to the left of the surface wind 
vector, while the thermal wind vector displaces it toward 
the southeast. This has the effect of augmenting the rate 
of turning in the one case, and reversing it in the other. 

Figures 2 and 3 show the observed shear vectors for 
the Little America data separated into frictional and 
thermal components in summer and winter. The frictional 
shear invariably has the effect of turning the wind vector 
to the left and increasing the speed with height. The 
amount of frictional turning of the wind vector from the 
surface to 1,000 m. varies from 17° to 28° in summer, 
and from 23° to 36° in winter. The seasonal difference may 
reflect greater hydrostatic stability in the boundary layer 
in winter, since the other effects on which the surface 
wind angle depends are either not applicable — variation 
with latitude — nor not very pronounced — variation with 
surface roughness (cf. Johnson [3]). 

The angles themselves are somewhat greater than would 
be expected from theory. A representative geostrophic 
wind speed of 550 cm. /sec, a Coriolis parameter of 
1.42X 10~ 4 sec." 1 , and surface roughness of 0.01 cm., which 
is typical of an Antarctic snow field, will produce an 
angle between the wind at the surface and at the top of 
the boundary layer of 15° (cf. H. Lettau [4]). 

The effect of the thermal wind is to turn the surface 
wind vector toward an azimuth of 91° in summer, and 
toward an azimuth of 42° in winter. The effect is less 
pronounced for north or south winds than for east and 
west winds in both seasons, presumably because the 
effect of the temperature gradient at the edge of the ice 
near Little America is suppressed within a homogeneous 
air mass moving perpendicular to the shore. The largest 
thermal shears occur with zonal winds in summer, when 
the ice edge is much closer to the station and of nearly 
east-west orientation. 

The change in direction of the thermal wind from sum- 
mer to winter is related to the magnitude of the annual 
temperature variation in the area surrounding Little 
America. A shift such as that observed requires a much 
greater seasonal temperature contrast to the west and 
southwest than to the east and northeast of the station. 



630 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 9 




WINTER 



I I I 



SE S SW 

Surface Wind Direct! 



Figure 4. — Source region temperature as a function of the surface 
wind direction. The shaded areas show the directions of minimum 
and maximum seasonal temperature contrast. 



Although the air temperatures in the vicinity of the 
station are not known directly, the seasonal contrast 
may be investigated by assuming that the mean temper- 
ature observed at the station with each wind direction is 
representative of thermal conditions some distance up- 
wind. As shown in figure 4, the seasonal temperature 
contrast does vary with the wind direction, ranging from 
a minimum of about 18° C. for north-northeast winds to 
a maximum of about 28° C. for winds generally from the 
west. It is suggested therefore that both the orientation 
of the thermal wind vectors and the change from summer 
to winter are direct results of the local temperature 
distribution, rather than spurious geometrical values 
introduced by the method of analysis. 

4. DETAILED WIND PROFILES 

A more complete representation of the boundary layer 
may be obtained by a detailed analysis of the observed 
wind profiles. Since the thermal wind is apparently 
insensitive to changes in wind direction, this section has 
been limited to the examination of the mean profiles 
observed with north and south winds at the surface for 
both the summer and the winter seasons. 

The theoretical background for the analysis of boundary 
layer wind profiles which include a constant thermal 
wind has been given by H. Lettau [5], H. Lettau and 



Hoeber [6], and Johnson [3]. The assumptions are made 
that the large-scale motion is uniform and unaccelerated 
over level terrain of constant surface roughness, that there 
are no mean vertical motions, and that there are no 
inertial forces, and that the vertical density variation 
can be neglected. The wind velocity is then a function 
only of the pressure gradient and the vertical derivative 
of the shearing stress. If the coordinate system is oriented 
with the y-axis parallel and the x-axis normal to the 
direction of the surface stress, which is also the direction 
of the surface wind, the vertical variation of the geo- 
strophic component parallel to the surface wind is con- 
strained by the fact that the surface stress has no compo- 
nent normal to they-direction, and that the shearing stress 
becomes negligible at height H. If v(z) is the observed wind 
profile in the y-direction, and V(z) the geostrophic wind 

profile in the same direction, then (V— v)dz=0. With 

the assumption of a constant thermal wind and geostrophic 
ambient conditions at z=H=l,000 m., V{z) is represented 
by a straight line tangent to v(z) at z= 1,000 m., such that 
the algebraic sum of the differences (V—v) (z) is zero. A 
similar line of reasoning will not give the analogous U(z) 
since the surface stress parallel to the surface wind is 
not zero. 

It is now possible to determine the vertical profile 
of 7V, 

T* = Pf£ (V-V)dz (1) 

where p is the air density, and/ is the Coriolis parameter. 
A similar expression can be written for t,„ 



l>- 



)dz 



(2) 



where U(z) is the geostrophic wind profile and u{z) the 
observed wind profile in the x-direction, although the 
relation is not very useful at the moment since neither 
the vertical profile of r„ nor that of U(z) is known. One 
may, however, also express the shearing stress at any 
level as the product of air density, wind shear, and eddy 
diffusivity. Both components of the wind shear are known 
and there is no reason to suppose the diffusivity to vary 
with direction. Thus for all values of z, 






du/bz 
'dv/dz 



(3) 



in which r„ is the only unknown. A convenient value to 
use is z=z*, the height at which V(z) and v(z) intersect, 
which is the height of maximum r x . Thus U(z) is obtained 
by the straight line tangent to ii(z) at 2=1,000 m., such 
that 



€ 



= P f\ (U-u)dz. 



(4) 



Figures 5 through 8 show the above constructions for 
smoothed mean northerly and southerly wind profiles in 



September 1967 

I000 



Bernhard Lettau 




6 7 8 

Wind Speed Parallel to Surface Wind Direction (mps 



—4 —3 —2 —I 

Wind Speed Normal to Surface Wind Direction (mps) 



Figure 5. — Observed ambient mean wind profile and computed linear geostrophic wind profile separated into components parallel and 

normal to the surface wind direction. North winds in winter. 



winter and summer. For the most part the differences 
among the four cases are minor, and related to directional 
rather than seasonal differences, suggesting that the ice 
surface produces its own characteristic wind distribution. 
The component parallel to the surface wind increases 
with height immediately above the surface in all four 
cases, but reaches a maximum below 400 m. and decreases 
slowly with height above that level. The geostrophic wind 
decreases continuously in the boundary layer indicating 
that this component of the thermal wind is antiparallel to 
the surface wind. Its magnitude however is relatively 
small, ranging from 0.3 to 1.5 m. sec." 1 km. -1 The height 
at which t t reaches a maximum is approximately 160 m., 
with the exception of southerly winds in summer when 



t x reaches a maximum at 200 m., and the maximum value 
attained ranges from 0.17 and 0.25 dyne/cm. 2 

The component normal to the surface wind shows a 
definite directional difference, caused by the relatively 
fixed thermal wind vector. For the southerly winds this 
component increases from the surface to roughly 500 m., 
then decreases to the top of the boundary layer, the devia- 
tion being to the left of the surface wind. For the northerly 
winds the component value in summer increases con- 
tinuously to the left of the surface wind through the 
boundary layer; in winter the profile is very similar with 
the exception of a slight relative maximum at 600 m. 
The geostrophic wind increases to the left for the northerly 
components, and to the right for the southerly components, 
implying an eastward-directed thermal wind for all cases. 



Table 2. — Derived boundary layer -parameters at Little America 



Height of maximum r ? .__ 

Surface geostrophic wind.. . . 

Surface stress.. 

Surface geostrophic wind angle. 
Thermal wind vector 

magnitude. . ... . . 

azimuth. 

Surface Rossby number 

Geostrophic drag coefficient.. 

Energy dissipation 

Roughness length 



V,o 



Ros 

C 

E 



m./sec. 

dyne/cm.- 

degrees 

m. sec.- 1 km.-i 
degrees 



watts/m.- 
cm. 



North Winds 
Winter Summer 



155 
8.78 
0.81 



1.72 
30 

8. 32 x 10° 
0.025 
0.61 
0.8 



160 
5.81 
0.64 
24 

1.24 
75 
2. 76 x 106 
0.033 
0.33 
1.6 



South Winds 
Winter Summer 



162 
6.23 
0.56 
23 

1.47 
108 
4. 57 x 10« I 
0. 030 
0.31 
1. 1 



202 
6.15 
0.94 
34 

1.42 
108 

0. 045 x 10 e 

0.041 

0.40 
105 



632 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 9 

000 



- 800 




-600 Z 



- 400 5 



- 200 



3 4 5 6—4 

Wind Speed Parallel to Surface Wind Direction (mps) 



—3 —2 

Wind Speed Normal to Surface Wind Direction (mps) 



Figure 6. — Observed ambient mean wind profile and computed linear geostrophic wind profile separated into components parallel and 

normal to the surface wind direction. North winds in summer. 



The magnitude of the normal component of the thermal 
wind is again relatively small, ranging from 0.8 to 1.4 m. 



sec. 



km." 1 



A number of other boundary layer parameters, given 
in table 2, may be determined either directly or sequen- 
tially from the observed and the geostrophic wind pro- 
files. Those determined directly include the surface 
geostrophic wind, \ gQ , obtained as the vector sum of the 
two geostrophic components at the surface, the surface 
stress, T , determined from the relation 



T0=f>f( (U-u)dZ 

,/n 



(5) 



and the angle, a , between the surface geostrophic wind 
and the surface stress, determined by the arctangent of 
the ratio U /V - Derived parameters include the surface 
Rossby number, Ro , which is a unique function of the 
angle a n , the geostrophic drag coefficient, C, determined by 
the relation 



r- h l 



(6) 



the energy dissipated in j the boundary layer, E, which 
may be obtained from the geostrophic wind and the 
surface stress (cf. H. Lettau [4]), and the roughness 
length, z , from the relation 



Zo-- 



'RooJ 



(7) 



The tabulated values are internally reasonably con- 
sistent with the exception of those parameter values de- 
rived from the surface geostrophic wind angle for the mean 
south wind profile in summer. The relatively much higher 
value for this angle produces a much lower surface Rossby 
number and consequently a much higher and quite 
spurious roughness length. 

Similar analyses of wind profiles in the boundary layer 
have been undertaken by Johnson [3] for kite wind data 
from four stations in the midwestern United States, and 
by H. Lettau and Hoeber [6] for pilot balloon profiles ob- 
tained on Helgoland in the North Sea. Although all three 
studies are in reasonable agreement with one another, re- 
sults of the first study are generally indicative of more 
vigorous flow over a rougher surface than that at Little 
America, while the second study shows more rapid air 
motion over a surface comparable to that at Little 
America. The differences in the surface stress and in the 
frictional energy dissipation within the boundary layer 
specifically emphasize these conclusions. At the inland 
stations in the first study the surface stress always exceeds 
0.8 dyne/cm. 2 and generally ranges from 1.5 to 2.0 dyne/ 
cm. 2 , while the energy dissipation generally exceeds 1 




Bernhard Letrau 




3 4 5 6 

Wind Speed Parallel to Surface Wind Direction (mps) 



-3 —2 —I 

Wind Speed Normal to Surface Wind Direction (mps) 



Figure 7. — Observed ambient mean wind profile and computed linear geostrophic wind profile separated into components parallel and 

normal to the surface wind direction. South winds in winter. 



watt/m. 2 On the ice shelf at Little America the stress 
ranges from about 0.6 to 0.9 dyne/cm. 2 , and the energy 
dissipation from 0.3 to 0.6 watt/m. 2 , lower by a factor of 
roughly three. The Helgoland data, which essentially 
represent wind profiles over a water surface, produce 
surface stress values of 0.6 and 0.9 dyne/cm. 2 , and energy 
dissipation values of 0.6 and 1.4 watt/m. 2 Since the sur- 
face stress value can be said to be determined by the shape 
of the wind profile components in the boundary layer, it 
is evident that these are roughly the same for the Helgo- 
land and the Little America data. The energy dissipation 
values, on the other hand, also depend on the mean geo- 
strophic wind in the boundary layer, which at Helgoland 
exceeds that at Little America by a factor of about two. 
Thus the observed difference is entirely due to the 
observed higher wind speed at Helgoland. 

The computed angles between the surface geostrophic 
wind and the surface stress in the Little America data 
do not follow the similarity pattern described above. 
These are more nearly equal to those found for the inland 
data, which average about 25°, than to those found for 
the littoral data (9.5° and 11.2°). From this point of 
view the ice shelf is better described as a land surface 
than as a water surface. 



A second point of similarity between the midwestern 
United States data and the Little America data is that 
the observed angles exceed by roughly 7° the values 
theoretically predicted by independently derived rough- 
ness lengths. If one takes the roughness length obtained 
as typical for the snow surface at the South Pole by 
Dalrymple et al. [1], 2 =0.014 cm., together with the 
observed wind speeds, one obtains a surface Rossby 
number of 3X10 8 , which corresponds to an angle between 
the surface geostrophic wind and the surface stress of 17°. 
The difference, as obtained by Johnson [3], was attributed 
to a real height variation of the thermal wind which 
would become obscured by the method of analysis, 
rather than to topographical or other external effects. 
A similar real height variation of the thermal wind 
should be expected in the Little America data because 
of the complex thermal structure of the boundary layer 
which would produce a number of abrupt wind velocity 
changes rather than the smooth transition that has been 
shown here. The diabatic effects which should be con- 
sidered on the ice shelf include radiational cooling near 
the ice surface, and temperature profiles which sometimes 
change from inversion to lapse conditions within the 
lowest 1,000 m. 



MONTHLY WEATHER REVIEW 




3 4 5 6-4 

Wind Speed Parallel to Surface Wind Direction (mps) 



-3 —2 

Wind Speed Normol to Surface Wind Direction (mps) 



Figure 8. — Observed ambient mean wind profile and computed linear geostrophic wind profile separated into components parallel and 

normal to the surface wind direction. South winds in summer. 



5. DISCUSSION 

A hypothetical example of precisely such diabatic 
influences on the wind spiral near a snow surface has been 
prepared by H. Lettau [4]. Here a surface cooling rate 
of 26 langleys/day produced a significant reduction in the 
surface wind speed, and a correspondingly greater angle 
between the surface stress and the surface geostrophic 
wind vector than under adiabatic conditions. Although a 
surface inversion is in fact one of the major characteristics 
of the Antarctic boundary layer, it is not possible to 
investigate this diabatic effect in the Little America I 
and II data, since almost no free-air temperatures were 
obtained by the Byrd Antarctic Expeditions. Subsequent 
scientific efforts in the Antarctic have of course obtained 
simultaneous temperature and wind profiles, although 
none has matched the nearly 1,000 boundary layer 
profiles that have been used in this study to provide 
reliable mean values. 



REFERENCES 

P. C. Dalrymple, H. H. Lettau, and S. H. Wollaston, "South 
Pole Micromctcorology Program, Part II, Data Analysis," 
Report No. 20, Institute of Polar Studies, Ohio State Univer- 
sity, 1963, 94 pp. 

G. Grimminger and W. C. Haines, "Meteorological Results of 
the Byrd Antarctic Expeditions 1928-30, 1933-35: Tables," 
Monthly Weather Review Supplement No. 41, 1939, 377 pp. 

W. B. Johnson, Jr., "Climatology of Atmospheric Boundary 
Layer Parameters and Energy Dissipation," Studies of the 
Three-Dimensional Structure of the Planetary Boundary Layer, 
Dept. of Meteorology, University of Wisconsin, 1962, pp. 
125-158. 

II. II. Lettau, "Notes on Theoretical Models of Profile Structure 
in the Diabatic Surface Layer," Studies of the Three-Dimensional 
Structure of the Planetary Boundary Layer, Dept. of Meteor- 
ology, University of Wisconsin, 1962, pp. 195-226. 

H. II. Lettau, "Windprofil, innere Ucibung, und Energic Umsatz 
in den unteren 500 m. iiber dem Mccr," Beitrdge zur Physik 
der Almosphdre, vol. 3D, No. 2, 1957, pp. 78-96. 

H. II. Lettau and II. Ilocber, "Uber die Bestiinmung der 
Hohenvertcilung von Schubspannung und Austauschkocffi- 
zienten in der atmospharischen Heibungsschicht," Beitrage 
zur Physik der Almosphdre, vol. 37, No. 2, 1964, pp. 105-118. 



[Received May SI, 1967; revised June 15, 1967] 



May 1967 



Reprinted from MONTHLY WEATHER REVIEW Vol. 95, No. 5 



299 



SEA-SURFACE TEMPERATURES IN THE WAKE OF HURRICANE BETSY (1965) 

JAMES D. McFADDEN 

Sea-Air Interaction Laboratory, Institute for Oceanography, ESSA, Silver Spring, Md. 



ABSTRACT 

Following the passage of hurricane Betsy (1965) through the Gulf of Mexico two flights were made five days 
apart aboard a research ah craft to collect sea-surface temperatures with an infrared radiometer. The purpose was 
to study the effects of a hurricane on the sea-surface temperatures field. Data from the first flight, which occurred one 
to two days after the hurricane passage, showed two cores of colder water to the right of the storm's track and very 
little structure to the left. The flight made five days later still showed a core of colder water to the right, but by this 
time its shape had been badly distorted by the surface current system. These results are compared with the findings 
of other investigators, and the value of real-time synoptic coverage with the use of aircraft is pointed out. The 
plan for an experiment utilizing aircraft and airborne oceanographic techniques to provide a 3-dimensional picture of 
the ocean temperature structure prior to and following a hurricane is also presented. 



1. INTRODUCTION 

There has been considerable interest shown in recent 
years in the effects of the passage of a hurricane on sea- 
surface temperature. While it is agreed that the hurri- 
cane causes a cooling of the sea surface of up to 5° C, 
there appears to be some disagreement as to the mechanics 
involved. Fisher [1] noted that pools of cold water were 
created behind some hurricanes during parts of their lives, 
and that this phenomenon is apparently produced by 
upwelling in the ocean where the top layers are thermally 
stratified. Jordan [5], working with ship temperature 
data obtained prior to and following several typhoons in 
the Pacific, concluded that vertical mixing is the primary 
factor in the cooling of the surface layers and that mechan- 
ical stirring is probably more important than organized 
upwelling in this cooling process. He reached these con- 
clusions mainly because the cooling was much more 
pronounced on the right side of the storm, (relative to 
the forward motion) the region of most intense wind and 
wave action. 

Stevenson and Armstrong [9], by measuring sea tem- 
peratures in a zone of low-salinity shallow water near the 
coast in the northwestern Gulf of Mexico after the pas- 
sage of hurricane Carla (1961), observed that bathy- 
thermograph traces revealed temperature inversions as 
great as 2.5° C. extending as deep as 83 m. They hy- 
pothesized that these inversions were formed in the surface 
waters through a lowering of the water temperature by a 
loss of heat to the hurricane. Leipper [7] made the most 
complete study to date in his detailed oceanographic 
investigation of that portion of the western Gulf through 
which hurricane Hilda (1964) passed. His observations 
indicated that the hurricane caused surface waters to be 
transported away from its center, cooling and mixing 



them to a slight degree as they moved. Convergence 
outside the storm area resulted in downwelling to 80 to 
100 m. in that area, while water on the order of 5° C. 
colder upwelled from about 60 m. in the central region of 
the storm. 

Hidaka and Akiba [3] developed a theory to explain 
cold water areas observed after hurricane passages which 
indicates a considerable amount of upwelling in the center 
of the storm. Ichiye [4], basing his results on fairly 
rigorous mathematical treatment, shows weak descending 
motion ahead of the storm, reaching somewhat larger 
though negligible values near the center, followed by 
strong vertical ascending motion thereafter. Gutman [2] 
and O'Brien [8] have also done some modeling of these 
phenomena. Gutman's solutions, which are obtained 
using variable stress as a function of time and then com- 
puting upwelling using continuity considerations, show 
maximum upwelling to occur at the center of the storm. 
O'Brien, on the other hand, derived a non-linear, theo- 
retical model which describes upwelling and mixing 
induced in a stratified, rotating two-layer ocean by mo- 
mentum transfer from a stationary, axially symmetric 
hurricane, and concluded that maximum upwelling occurs 
in the region of maximum turbulent shearing stress. 
O'Brien, however worked with a stationary model while 
Gutman incorporated forward movement of the system 
in his model. 

Thus, some question remains as to the origin of these 
cold spots observed in the wakes of hurricanes. Leipper's 
conclusion that upwelling is responsible is certainly rea- 
sonable based on the results of his cruise following the 
passage of hurricane Hilda (1964), but his inference that 
this upwelling occurred in the central region of the storm 
is still not completely proven. The "after Hilda" data 



300 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 5 



were collected on a seven-day cruise, which means that 
the information obtained was not synoptic. Uncertainties 
of interpretation may have resulted from the fact that no 
consideration was given to the effects of the Gulf circu- 
lation on the thermal structure in the interval between 
the passage of the hurricane and the time the observations 
were made. 

2. OBJECTIVES 

During the past 12 yr. there have been only 11 hur- 
ricanes that have qualified as "great hurricanes", i.e., 
hurricanes with central pressure less than 950 mb. (Kraft 
[6]). Hurricane Betsy (1965) was one of these. It had 
qualified for this category before entering the Gulf of 
Mexico on September 8 and continued as an intense 
storm until shortly after landfall on September 10. Its 
maximum surface wind speed averaged about 120 kt. 
during the Gulf transect, and the eye diameter varied 
between 25 and 80 n. mi. during this period (see fig. 1). 

Because of the size and intensity it was immediately 
recognized that this storm should have a profound effect 
on the thermal structure of the surface of the ocean. 
On September 9, the Director of the National Hurricane 
Research Laboratory, ESSA, agreed to support the Sea 
Air Interaction Laboratory's efforts to study these 
effects by making available a research aircraft from 
ESSA's Research Flight Facility for two nights to obtain 
sea-surface temperature data with an infrared radiometer 
in the wake of the storm. These missions were successfully 
completed on September 10 and 15. 

The objective of this paper is to present the essentially 
real-time sea-surface temperature patterns obtained from 
these two flights, to discuss the similarities and differences 
between these results and those of previous investigators, 
and to suggest an investigation that could possibly lead to 
a more thorough understanding of the effects of the 
storm on the ocean thermal structure. 



3. DATA COLLECTION 

ESSA's Research Flight Facility is adequately equipped 
with multi-engine aircraft (two DC-6's, a DC-4, and a 
B-57) suitable for long-range reconnaissance and especially 
for hurricane research. The aircraft are outfitted with 
a system of meteorological sensors, radars, and photo- 
graphic equipment as well as digital tape, analog, and 
photo-recording devices. For obtaining sea-surface tem- 
peratures from the DC-6 aircraft a Barnes IT-2 radiom- 
eter is employed, and the infrared (IR) data are recorded 
on an oscillographic recorder. This sensor is shock 
mounted vertically on a frame which fits inside the drop- 
sonde chute during normal operation but which can 
easily be removed at any time during flight in order that 
in-flight calibration checks of the radiometer can be 
made. Two-point calibration checks are made ap- 
proximately every 30 min. during flight using two agitated 




FLIGHT TRACK 10-11 SEPT 1965 
ALONG PATH OF HURRICANE BETSY 






Figure 1. — Flight track of September 10-11, 1965, superimposed on 
the path of hurricane Betsy. Dashed lines define width of eye as 
determined by radar and reconnaissance aircraft. 




SEA SURFACE TEMPERATURE 
DISTRIBUTION 10-11 SEPT 1965 

+ MERCHANT SHIP DATA 
(WithinJ2 hr. of IlighMilt 

I 






Figure 2. — Sea-surface temperature distribution on September 
10-11, 1965. 



water baths of different temperatures. This rather 
frequent calibration helps to minimize readout errors 
resulting from changes in detector bias voltages, detector 
responsivity, amplifier gain, and amplifier drift of the 
radiometer. Such changes otherwise could lead to errors 
in the analysis of the data, which from experience could 
be as much as 1.5° to 2° C. 

The track of the first flight, superimposed over the path 
of Betsy, is shown in figure 1. The times of three turning 
points are given for comparison with the hurricane time 
coordinates. The dashed lines denote the eye width as 



May 1967 



James D. McFadden 



301 



determined by radars at Key West and New Orleans and 
by reconnaissance aircraft. Greater emphasis was placed 
on the right side of the storm track, although the left 
portion was adequately covered for detection of any 
colder water zones in that region. 

A DC-6 research aircraft departed Miami on September 
10 at 2225 gmt and returned after completing the 
mission at 0600 gmt on September 11. A flight altitude of 
between 800 and 1000 ft. was maintained throughout 
the flight. In addition to the IR data, meteorological 
information was also obtained throughout the flight at a 
sampling frequency of once every 10 sec. This information 
included: temperature, pressure, humidity, pressure alti- 
tude, radar altitude, and wind direction and wind speed as 
determined by the Doppler navigational system. Precise 
positioning was provided by means of Loran. The second 
flight on September 15, with the exception of the flight 
track, was conducted in the same manner as the first 
flight, 

4. RESULTS 

The sea-surface temperature distribution as measured 
on September 10-11 is shown in figure 2. The solid 
lines are isotherms drawn with a reasonable degree of 
certainty while the dashed lines, exclusive of the eye 
size indication, are extrapolated isotherms. The four 
temperatures at positions denoted by plus signs were 
obtained by merchant ships within 12 hr. of the time in 
which the IR data were collected. They were not used 
in analyzing the data and positioning the isotherms and 
are presented only for comparison with the airborne IR 
measurements for this flight, 

At a glance the cold water zone induced by the hur- 
ricane is immediately the outstanding feature of this 
figure. It may be noted, however, that all of this cold 
water appears to the right of Betsy's path and farther 
from the center than the eye wall. Another interesting 
feature is the existence of two cores of cold water rather 
than one continuous trough. The northward curl of 
isotherms in the eastern core is of importance as will be 
shown below. The lowest temperature detected by the 
radiometer was slightly less than 25° C. This indication 
was recorded several miles north of the intersection of 
the leg of the flight occurring after the 2331 gmt turning 
point with the leg made prior to the 0404 gmt turning 
point on both tracks. The temperatures recorded on 
both tracks at each of the two intersections were in 
agreement with each other, thus indicating relative 
validity of all of the IR flight data. 

Based on preliminary results of the first flight, a second 
plan was drawn up to cover some of the major features 
which had been observed. Major emphasis was placed 
on the north (right) side of the hurricane's path. At 
0500 gmt on September 15, a DC-6 research aircraft 
departed Miami on another mission to collect sea-surface 
temperature data. Figure 3 shows the track of that 




FLIGHT TRACK 15 SEPT 1965 



Figure 3. — Flight track of September 15, 1965, superimposed on the 
path of hurricane Betsy. 




Figure 4. — Sea-surface temperature distribution on September 15, 

1965. 



flight, The aircraft returned to Miami at 1200 gmt 
after completing the second of the two nighttime flights 
made during the operation. 

The major feature of the second flight shown in figure 
4 is an elongation to the northeast of the cold core detected 
on the earlier flight as indicated by the northward curl 
of the isotherms shown in figure 2. The data also indicate 
that during the five-day interval between flights the 
cold-core surface temperatures increased about 0.5° 
to 1.0° C. 

Another interesting feature is the relatively small 
cold water area southwest of St. Petersburg and Tampa 
Bay. The shape of the isotherms indicates that this 



302 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 5 



temperature structure is possibly associated with the 
bay circulation and may result from relatively cool rain- 
water runoff. 

On the latter flight the aircraft did not traverse the 
area of the Gulf where the second cold core was detected 
on the western legs of the first flight. 

5. CONCLUSIONS 

The results of this experiment lead to two conclusions. 
First, they confirm the observations of the other investi- 
gators, as was expected, that hurricanes do cause well 
defined areas of cold water to occur at the sea surface 
in their wakes. The surface temperature data alone, 
however, do not establish whether maximum upwelling 
occurs in the central region of the storm, as concluded 
by Gutman [2] and Leipper [7], or whether it occurs in 
the region of maximum turbulent shearing stress as 
concluded by O'Brien [8]. Certainly the positions of 
the cold water areas observed on these flights fit more 
closely positions of cold water zones described for Pacific 
typhoons by Jordan [5], but again it is not obvious from 
the IR data that vertical mixing induced by mechanical 
stirring is more important than organized upwelling in 
this cooling process as he concluded. 

Perhaps even more important than the first observation 
above, at least from a data collection standpoint, is the 
rapid deformation of the eastern cold water core observed 
in the interval between the two flights. This temperature 
pattern change could have been realized by a northeast- 
ward flowing current of less than 1 kt. Such a current, 
the Yucatan Current, is a feature of the surface circulation 
of the Gulf of Mexico. 

The emphasis here is on the sampling time involved in 
acquiring data for the solution of this particular problem. 
On the one hand a research ship can obtain, in addition 
to surface temperatures, sub-surface data which are 
essential to answering the questions concerning upwelling 
and mixing. A voyage to obtain this information, how- 
ever, requires a considerable amount of time — about 10 
days to cover such an area as discussed here. 

The aircraft, on the other hand, covered the area in 
less than 10 hr., but it was not suitably equipped to 
obtain sub-surface temperatures. It would be desirable, 
then, to combine the speed of the aircraft with the 
versatility demonstrated by the ship for success! ully 
attacking the problem. Wilkerson [10] points out that 



with an airborne infrared sensor and an air-droppable 
expendable bathythermograph, observations can now be 
made of sea-surface temperatures and temperatures with 
depth, thus providing a near-synoptic picture of the 
thermal structure of the first few hundred meters of the 
ocean over a large area. It would take several ships at 
considerably greater expense to duplicate such observa- 
tions. The Sea-Air Interaction Laboratory plans in the 
near future to employ these techniques of airborne 
oceanography in a more detailed synoptic study of the 
effects of a hurricane on the thermal structure of the ocean 
by measuring surface and sub-surface temperatures both 
ahead of and behind the storm. 

ACKNOWLEDGMENTS 

The author expresses his thanks to the National Hurricane 
Research Laboratory for making the flight time available, to 
ESSA's Research Flight Facility, in particular to Dr. Gerald 
Conrad, for collecting the data, and to Mr. Feodor Ostapoff and 
Dr. Donald V. Hansen of the Institute for Oceanography for their 
comments and suggestions. 

REFERENCES 

1. E. L. Fisher, "Hurricanes and Sea-Surface Temperature Field," 
Journal of Meteorology, vol. 15, No. 3, June 1958, pp. 328-333. 

2. G. Gutman, "A Preliminary Study of Ocean Conditions as 
Affected by a Hurricane Passage," Paper presented at the 
Fourth Technical Conference on Hurricanes and Tropical 
Meteorology, Miami Beach, Fla., Nov. 22-24, 1965. 

3. K. Hidaka and Y. Akiba, "Upwelling Induced by a Circular 

Wind System," Records of Oceanographic Works ■ in Japan, 
vol. 2, No. 1, Mar. 1955, pp. 7-18. 

4. T. Ichiye, "On the Variation of Oceanic Circulation, Part 5," 
Geophysical Magazine, Tokyo, vol. 26, No. 4, Aug. 1955, pp. 
283-299. 

5. C. L. Jordan, "On the Influence of Tropical Cyclones on the 
Sea Surface Temperature Field," Proceedings, Symposium on 
Tropical Meteorology, J. W. Hutchins (ed.), New Zealand 
Meteorology Service, Wellington, 1964, pp. 614-622. 

6. R. H. Kraft, "Great Hurricanes, 1955-1965," Mariners Weather 
Log, vol. 10, No. 6, Nov. 1966, pp. 200-202. 

7. D. F. Leipper, "Observed Ocean Conditions and Hurricane 
Hilda, 1964, "Journal of the Atmospheric Sciences, 1967 (in press). 

8. J. J. O'Brien, "The Non-Linear Response of a Two-Layer, 

Baroclinic Ocean to a Stationary, Axially-Symmetric Hurri- 
cane," Texas A&M University, Department of Oceanography, 
Reference 65-34T, Dec. 1965, 98 pp. 

9. R. E. Stevenson and R. S. Armstrong, "Heat Loss From the 
Waters of the Northwest Gulf of Mexico During Hurricane 
Carla," Geofisica Internacional, vol. 5, No. 2, 1965, pp. 49-57. 

10. J. W. Wilkerson, "Airborne Oceanography," Geo-Marint 
Technology, vol. 2, No. 8, Sept. 1966, pp. 9-16. 



[Received February 9, 1967 ; revised March 3, 1967] 



936 



Reprinted from MONTHLY WEATHER REVIEW Vol. 95, No. 12 



Vol. 95, No. 12 



COMPATIBILITY OF AIRCRAFT AND SHIPBORNE INSTRUMENTS USED IN AIR-SEA 

INTERACTION RESEARCH 

JAMES D. McFADDEN 

Sea Air Interaction Laboratory, ESSA, Silver Spring, Md. 

and 

JOHN W. WILKERSON 

U.S. Naval Oceanographic Office, Washington, D.C. 

ABSTRACT 

On June 16, 1966, an experiment was performed off the east coast of Florida that involved two research aircraft, 
one from the Naval Oceanographic Office and one from ESSA's Research Flight Facility, and the USCGSS Peirce, 
aboard which were two scientists from ESSA's Sea Air Interaction Laboratory, and the Weather Bureau Airport 
Station at Jacksonville, Fla. The purpose of this investigation was to determine the comparability of data for air-sea 
interaction research as determined by aircraft temperature, humidity, pressure, and wind sensors; airborne IR radiom- 
eters; a tethered boundary layer instrument package, radiosondes, rawinsondes, and dropsondes. Results showed 
generally good agreement (within listed instrumental accuracies) between comparisons of aircraft and radiosonde 
temperature and humidity observations, fair agreement of wind observations, and very poor comparisons between 
dropsondes and radiosondes. The sea surface temperature readings obtained by the airborne radiation thermometer 
aboard the Navy aircraft were well within ±0.4° C. operational accuracy of the instrument when compared with 
bucket temperature measurements taken aboard the Peirce. Whether the accuracies of these presently available 
instruments are good enough for mesoscale and macroscale ocean-atmosphere interaction investigations now being 
planned will have to await studies of the environments in which these experiments will take place. 



1. INTRODUCTION 

A major, comprehensive, field investigation is now being 
planned by ESSA, the primary focus of which will be on 
the problem of ocean-atmosphere interaction, as well as 
related topics in physical oceanography and microscale 
and mesoscale meteorology. The primary objectives of 
this experiment are: 1) to study the total fluid environ- 
ment within a limited area, and 2) to provide a realistic 
pilot field study for the planning and execution of a suc- 
ceeding major Tropical Ocean Area Study within the 
framework of the World Weather Watch. 

The plans for this experiment call for among other things 
the deployment of several ships on fixed stations several 
hundred miles apart, a roving ship for making meteorolog- 
ical and oceanographic measurements within the study 
area, and several research aircraft that will be used in a 
variety of measurement programs, such as vertical pro- 
filing, making line integral observations, and obtaining 
sea surface and subsurface temperature data. Further, 
these plans call for the utilization of ship launched 
rawinsondes, for obtaining vertical soundings of temper- 
ature, pressure, humidity, and winds; tethered boundary 
layer instrument packages for obtaining both profiles of 
temperature, humidity, pressure, and winds and the time 
variation of these quantities at any height up to 2000 m.; 
and air released dropsondes for obtaining vertical profiles 
of temperature, humidity, and pressure. 



Before the investigation can be initiated, however, there 
are certain preliminary steps that must be taken. These 
include: 1) an evaluation of the compatibility of the 
variety of instruments mentioned above, 2) an improve- 
ment in our knowledge of the environment in the region 
of the experiment, and 3) a test of the major instrument 
systems in the experimental area. This paper concerns 
itself with the first of these steps. 

In June 1966 an experiment was performed to evaluate 
the comparability of existing operational instruments of 
the types planned for use in future mesoscale and macro- 
scale ocean-atmosphere interaction studies. The objectives 
of this investigation were to observe the comparability of 
the data obtained by the various methods mentioned 
above, to ascertain whether observed differences between 
any two readings of a given parameter were within the 
quoted accuracies of the measuring instruments, and to 
arrive at a conclusion regarding the use of these state-of- 
the-art instruments for air-sea interaction research. 

2. INSTRUMENTATION AND DATA ACQUISITION 

Because of the nature of this experiment a variety of 
organizations was called upon to pool their efforts toward 
accomplishing the mission. The U.S. Naval Oceano- 
graphic Office provided the services of its Ocean Aerial 
Survey Unit of the ASWEPS program and ESSA was 
represented by the Weather Bureau Airport Station at 
Jacksonville, Fla., the USCGSS Peirce, the Research 



December 1 967 



James D. McFadden and J. W. Wilkerson 



937 



Flight Facility (RFF) of the Institute for Atmospheric 
Sciences, and the Sea Air Interaction Laboratory (SAIL) of 
the Institute for Oceanography. 

The Navy aircraft was a Lockheed Super-G Constella- 
tion which, as one of the airborne platforms, was used to 
obtain measurements of air temperature, pressure, and 
humidity and sea surface temperature. The air tempera- 
ture and pressure aboard this aircraft are obtained by a 
meteorological set (AN/AMQ 17) which consists in pari 
of a platinum wire resistor vortex thermometer and a 
bellows mechanically linked to a potentiometer. The 
operational accuracies listed for this device are 0.5° C. 
for the thermometer and 5 mb. for the pressure sensor. 

Humidity data are obtained by an infrared absorption 
hygrometer system designed and built by the Weather 
Bureau's Equipment Development Laboratory. Basically 
this hygrometer is an optical instrument designed to 
measure the absolute humidity of the atmosphere by 
measuring the absorption of radiant energy over a given 
optical path in the spectral region of the infrared water 
vapor absorption band. A full description of this system 
is given in [1]. 

A relatively large console model airborne radiation 
thermometer (ART) developed by Barnes Engineering 
Co. is used to obtain sea surface temperature aboard 
the Navy aircraft. Radiation from the sea surface in the 
8 to 13-/z region is detected by a thermistor bolometer 
and this received energy, which is proportional to the 
fourth power of the sea surface temperature, is translated 
into temperature readings by electronic processing. The 
operational accuracy of this system is listed as ±0.4° C. 

These instruments represent just three of a large array 
of devices designed for oceanographic research from the 
Navy aircraft. A complete description of this aerial 
platform and its capabilities is given in [2]. 

ESSA's Research Flight Facility provided this project 
with a DC-6 aircraft instrumented primarily for hurricane 
research. This aircraft was used as a platform from which 
air temperature, pressure, and humidity; wind speed 
and direction; and sea surface temperatures were obtained 
and from which dropsondes to measure temperature, 
pressure, and humidity were released. 

An AMQ-8 vortex thermometer system is used aboard 
the RFF aircraft to measure the free-air temperature 
in flight. System accuracy is quoted to be 0.5° C. Ambient 
pressure is measured by a pressure transducer operating 
on an independent static source. 

Humidity is measured by a system identical to that 
described for the Navy aircraft. An interesting secondary 
objective of this experiment was to obtain data from which 
a thorough evaluation of the in-flight capabilities of these 
two absorption hygrometers could be made. The infrared 
hygrometer, while used on both aircraft as the primary 
source of humidity information, is still classed as a 
special purpose device. It has three outstanding features 
that make it desirable for use aboard aircraft, high 



sensitivity at low water-vapor concentrations, fast speed 
of response for all water-vapor concentrations, and ability 
to effect a humidity measurement without altering the 
sample concentration by either adding or subtracting 
water or changing the state of any part of the sample. 

Wind speed and direction, along with latitude and 
longitude information, are determined by a Doppler 
navigation and wind-computing system (APN-82) manu- 
factured by General Precision Laboratories. The Research 
Flight Facility, from operational experience quotes for 
this system an accuracy of ± 3 kt. for the wind speed 
and an error function in degrees of roughly (150 -h- wind 
speed) for wind direction. 

The dropsonde system used aboard the RFF DC-6 
is a military type (AN/AMT-3) and is used to obtain 
soundings of temperature, pressure, and humidity from 
aircraft flight level to the surface. Following launch from 
the aircraft the instrument descends by parachute at a 
rate of approximately 1,200 ft./min. During this descent 
the package transmits measurements of temperature, 
humidity, and pressure in International Morse Code 
approximately 12 times a minute, and these transmissions 
are hand copied aboard the aircraft. 

The temperature element consists of a bimetallic strip, 
the humidity element of several strips of hair; and the 
pressure element is a double-bellows aneroid cell. RFF 
experience with this system indicates that pressures 
determined by this instrument are accurate to within plus 
or minus 2 mb., and that temperature and humidity 
data are comparable in accuracy to conventional radio- 
sondes. 

To obtain sea surface temperatures the RFF employs 
a Barnes IT-2 infrared thermometer. In principle this 
device operates similarly to the ART on the Navy aircraft, 
being a thermistor bolometer with a spectral bandpass 
of 8 to 13 /x. Physically, however, the unit is much smaller 
and can be hand held. The sensing head of the radiometer 
is mounted in the dropsonde chute of the DC-6. A more 
detailed description of its operation is given in [3]. The 
manufacturer lists a resolution of 1° F. and an absolute 
accuracy of 2° F. for this instrument. 

The USCGSS Peirce was used as a platform from which 
scientists from SAIL launched conventional radiosondes, 
obtained sea surface temperatures for comparison with 
aircraft infrared-sensed temperatures, and gathered air 
temperature and humidity data at 1,000-ft. and 500-ft. 
heights with a boundary layer instrument package being- 
developed in-house. This device, which was in the early 
stages of development at that time, consisted of a stand- 
ard 403-mHz. radiosonde package supported at the given 
heights by a pair of kytoons tethered to the ship. The 
aneroid switch had been replaced with a small clock 
switch and this permitted alternate transmission of tem- 
perature and relative humidity data to a standard radio- 
sonde receiver-recorder located on the ship. (Subsequent 
to this experiment a more sophisticated package has been 
developed by SAIL which can be used to measure and 






938 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 12 



transmit temperature, humidity, and wind speed data 
simultaneously to receivers on the ship from any height 
from the surface to 2000 m. The development of this sys- 
tem is the subject of a forthcoming report now in prepara- 
tion within the laboratory.) 

The Weather Bureau participation in this experiment 
consisted of a rawinsonde launch from the Airport Station 
at Jacksonville, Fla. A 1200-gm. balloon was released at 
this station shortly before the arrival of the aircraft over 
Jacksonville and was tracked by GMD radar to an 
altitude of about 32,000 ft. Air temperature, pressure, and 
humidity, of course, were also obtained on this flight. 

On June 16, 1966, under ideal weather conditions the 
instrument comparison test was performed. The operation, 
as shown in figure 1, proceeded in the following manner. 
The two aircraft departed Miami, Fla., about 1345 gmt 
and proceeded at an altitude of 5,000 ft. to a point north 
of Cape Kennedy staying a few miles inland at all times. 
This route was necessitated by a launch from the Cape 
which had been rescheduled from the prior day. After 
reaching this point the research aircraft turned eastward, 
descended to 1,000-ft. altitude and continued on the 
course shown to the USCGSS Peirce while maintaining a 
separation between them of 2 to 3 mi. Upon arriving at 
the ship and making an initial pass past the boundary 
layer instrument package tethered at 1,000 ft. the RFF 
aircraft began its climb to the 500-mb. level while the 
Navy aircraft made three additional passes over the 
Peirce before beginning its climb. 

After completing the ascent to the desired altitude, 
personnel aboard the DC-6 released a dropsonde while 
simultaneously a radiosonde was released from the ship. 
By the completion of the radiosonde and dropsonde 
soundings the Navy plane had arrived at the same level 
as the RFF aircraft, and both planes began a 500-ft./min. 
spiral descent to 500 ft. where four additional passes were 
made over the ship. A southwesterly flight path was then 
followed from the Peirce to Jacksonville, Fla. Enroute, 
the Navy plane flew at an altitude of 1,000 ft. collecting 
sea surface temperature data while the RFF plane 
climbed to 15,000 ft. for a second dropsonde release about 
halfway between the ship and the airport station. After 
reaching Jacksonville the DC-6 made a short ascent to 
18,000 ft. and released a third dropsonde, as indicated in 
figure 1, while the Constellation was completing its climb 
from 1,000 ft. to the same height. Both aircraft then made 
a spiral descent as described before to 1,000 ft. just 
seaward of the coast and east of Jacksonville. After 
completing the spiral descent, the Navy Constellation 
terminated its data acquisition operation and returned to 
its home base at Patuxent River, Md. The RFF DC-6 
proceeded on a southerly course toward its home base at 
Miami, breaking off data acquisition at Daytona Beach. 

3. RESULTS 

Figures 2-8 and table 1 present the results of this 
experiment. A quick glance at these graphs makes it 



CLIMB & DESCEND 
US C&GS 
PIERCE 




Figure 1. — Flight plan of Navy and Research Flight Facility 
aircraft on June 16, 1966. 



Table 1. — Comparison of aircraft sensors with boundary layer 
instrument package and sea surface temperature thermometer 





Air temperature 


(°C.) 


Humidity 


(gm./m. 3 ) 


Sea surface 
temperature (°C.) 


Altitude(ft.) 


Navy 


RFF 


Peirce 


RFF 


Peirce 


Navv 
(ART) 


Peirce 
(Bucket) 


1000 


24.0 
23.8 
23.7 
23.7 
24.6 
24.6 
24.7 
24.7 


24.0 

a 

e 

5 

24.8 
24.8 
24.8 
24.6 


24. 1 
24.3 
24.0 
25.1 
24.7 
25.0 
25.0 


IS. 3 
No data 




27.3 
27.3 
27.3 
27.3 
27.4 
27.4 
27.4 
27.5 


27.2 






27.4 






27.4 








27.3 


500 


18.5 
18.5 
18.5 
18.5 


16.8 
16.1 
15.0 
16.8 


27.3 
27.2 
27.3 

27.3 



December 1967 



James D. McFadden and J. W. Wilkerson 



939 



immediately apparent that there are no data for some of 
the instruments originally planned to be used and de- 
scribed in the previous section. Unfortunately, there were 
equipment malfunctions during the flight and even more 
unfortunate no back-up systems for substitution. This 
will be discussed further, later. 

Figure 2 depicts sea surface temperatures measured by 
the ART on the Navy plane and a plane-to-plane compari- 
son of air temperatures on the Cape Kennedy-to-ship leg 
of the flight. As mentioned earlier the lateral separation 
between the two aircraft was 2 to 3 mi. which possibly 
could account for some of the observed differences 
(maximum 0.5° C.) in the air temperature record. 

Perhaps the greatest interest, particularly in the Navy 
Oceanographic Office and the Research Flight Facility, 
lay in the comparison of the infrared radiometers and the 
absorption hygrometers of the two aircraft. It is sad to 
say that neither of these comparisons could be made 




AIR TEMPERATURES 

NAVY AIRCRAFT 
RFF AIRCRAFT 




1530 1540 



1550 1600 



Figure 2. — Sea surface temperatures as measured by Navy ART 
and air temperatures as measured by both aircraft on Cape 
Kennedy to USCGSS Peirce leg of the flight. 



























\J 








\ 






RFF 

NA\ 


AIRCRAFT 
r AIRCRAFT 








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Figure 4. 



-Comparison of radiosonde temperature profile 
RFF aircraft profile. 



with 



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OROPSONDE 








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20 30 



Figure 5. — Comparison of radiosonde and dropsondc temperature 
sounding. 



500 














1 




If 
1 

1 \ 
1 J 
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!V JAX 






\ SHIP 


RADIOS 


ONDE 






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HUMIDITY (G/M J 



Figure 3. — Comparison of air temperature profiles measured by Figure 6. — Comparison of RFF aircraft and radiosonde humidity 
both aircraft. sounding. 



940 



MONTHLY WEATHER REVIEW 



Vol. 95, No. 12 



















I I 

RFF AIRCRAFT 

JAX RAWINSONDE 


500 








































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90 180 270 

WIND DIRECTION (DEG ) 



WIND SPEED (M/SEC) 



Figure 7. — Doppler determined wind direction and speed compared 
with rawinsonde data at Jacksonville, Fla. 




20 30 



TEMPERATURE °C 



Figure 8. — Aircraft temperature profiles for the two stations com- 
pared with the radiosonde profiles. 



because of the malfunction inflight of one of these systems 
on each aircraft. The Barnes IT-2 radiometer failed only 
moments after crossing the coastline just north of the Cape 
and could not be repaired aboard the plane. On the other 
hand, the infrared hygrometer on the Navy plane mal- 
functioned shortly after takeoff and its ailment was not 
diagnosed until the Constellation returned to its home 
base at Patuxent River, Md. The Navy plane has a 
backup system for humidity measurements — part of the 
AMQ-17 system described earlier — but it was not opera- 
tional that day. Thus, no humidity measurements were 
obtained by this group. The RFF had no backup IR unit 
for its aircraft and thus sea surface temperatures were not 
obtained by that group. 

Comparisons of certain aircraft sensors with an early 
version of SAIL's boundary layer instrument package and 



of the Navy ART and Peirce bucket sea surface tempera- 
tures are shown in the table. Here, plane-to-plane compari- 
sons of air temperature are excellent and plane-to-boundary 
layer package comparisons are reasonably good for the 
Navy's 1,000-ft. passes and very good for the 500-ft. 
passes of both airplanes. The humidity data are not too 
comparable, and the fluctuations by the amounts shown for 
the boundary layer package for the 1-min. intervals 
between measurements indicate that part of the difference 
may have been a result of relative humidity measurement 
errors in the package sensor. The IR sea surface tempera- 
ture readings certainly are within the ±0.4° C. accuracy 
figure quoted by the Navy. 

Figures 3 through 5 show the results of the vertical 
profiles of air temperature obtained by the aircraft, radio- 
sondes, and dropsondes over the ship and at Jacksonville. 
Certainly one must agree that the aircraft comparisons 
are the best of the lot, although a large part of the differ- 
ences observed in the aircraft-radiosonde comparisons can 
be rationalized away. The fact that the radiosonde read- 
ings over the ship are consistently higher than the aircraft 
readings might be attributed to trouble in obtaining a 
baseline check aboard the ship, as was indicated by one 
of the scientists making the launch. The excellent com- 
parison at Jacksonville was obtained even though the 
radiosonde was launched at the airport and the aircraft 
profile was made several miles offshore or a total distance 
of about 20 n.mi. 

The dropsonde-radiosonde comparisons of air tem- 
perature are so poor that figure 5 really should not receive 
further comment. The large observed differences may be 
attributed to calibration errors or improper baseline 
checks for the dropsonde, although it seems unreasonable 
that these errors would have caused the odd shapes of the 
dropsonde soundings. Whatever the cause, the fact that 
one unit was 12 yr. old and the other 14 yr. old probably 
did not help the situation. At any rate this comparison 
should be made again with newer equipment. 

The humidity profiles shown in figure 6 are given as 
absolute humidity (gm./m. 3 ). For the radiosonde, absolute 
humidity was computed from the temperature and relative 
humidity data, thus presenting a possible double source 
of error. The 2- to 3-gm./m. 3 differences observed in the 
soundings could be a result of temperature and relative 
humidity errors in the radiosonde and/or some error in 
the infrared hygrometer system on the aircraft. Again, 
it was unfortunate that the second hygrometer system 
was not available. 

Because of the large differences between the radiosonde 
and dropsonde air temperatures and the use of this para- 
meter along with relative humidity to compute absolute 
humidity, no comparison was made of the humidity data 
from these two sources. Possibly a future experiment 
will permit such a comparison. 

The comparison of the Doppler wind system aboard 
the RFF DC-6 with the winds-aloft data from the Jackson- 
ville rawinsonde are shown in figure 7. Generally, for wind 



December 1967 



James D. McFadden and J. W. Wilkerson 



941 



direction the agreement above the 920-mb. level is reason- 
ably good, the observed differences at most points being 
within the accuracy limits quoted for the Doppler system. 
This system, however, shows rapid fluctuations in wind 
speed throughout the profile whereas the rawinsonde 
data have a smoothed appearance. This, of course, is 
due to the fact that individual point readings for rawin- 
sonde wind data represent layer averages while Doppler 
readings are instantaneous values. 

4. CONCLUSIONS 

What do these results mean in terms of air-sea in- 
teraction studies? Surely, one recognizes that a more 
uniform region, in terms of atmospheric parameters and 
oceanic thermal conditions, places much more stringent 
requirements on instrumental accuracies than an area 
where there are large horizontal gradients of temperature 
and moisture. One also realizes that accuracy requirements 
are much greater where single samples are used as op- 
posed to the cases where many samples are averaged. 
With respect to this experiment these considerations 
can be applied to the comparison shown in figure 8. 
Here is shown a comparison of the vertical profiles of air 
temperature at the ship and at Jacksonville, Fla., as 
obtained in one case by the RFF aircraft and in the 
other case by radiosonde measurements. Such a com- 
parison could be made because the ship and Jacksonville 
happened to fall on a line essentially parallel with the 
wind trajectory (see fig. 7). 

There are a couple of things worth noting in this 
figure. First, for practically the whole of both soundings 
the observed differences between the Jacksonville station 
and the ship station are so small that they might rep- 
resent instrumental inaccuracies rather than air tem- 
perature changes. Second, note that for the layer between 
660 and 830 mb. the aircraft soundings show almost 
no net change in temperature while the radiosonde 



soundings show a significant temperature increase. Thus 
for an environment such as was found east of Jacksonville 
in June, instrumental accuracies would be of major 
concern. 

It is fair to conclude from the results, then, that aircraft 
and radiosonde measured air temperatures, and possibly 
humidities also, were within the accuracies stated for the 
sensors. Another look at the dropsonde should be taken 
before it is accepted for air-sea interaction studies. A 
further development of SAIL's boundary layer instrument 
package should provide more accurate instrumentation 
for boundary layer research. 

Again, it is emphasized that this experiment was pri- 
marily intended to show what the available instruments 
could do. Whether they will be suitable for the ocean- 
atmosphere interaction investigations now being planned 
must await studies of the environment in which the ex- 
periments are planned. 

ACKNOWLEDGMENTS 

The authors wish to acknowledge the cooperation and help of 
the officers, crew, and scientific personnel of the Navy aircraft 
El Coyote, of the RFF aircraft 39-Charlie, of the USCGSS Peirce 
and the Weather Bureau Airport Station at Jacksonville, Fla. 
A special note of thanks is given to Michael Bratnick of the Naval 
Oceanographic Office and to Monte Poindextcr and Frank Shibuya 
of the Sea Air Interaction Laboratory for their help in processing 
the data. 

REFERENCES 

1. W. F. Staats, W. W. Foskett, and H. P. Jensen, "Infrared 

Absorption Hygrometer," Humidity and Moisture, Measure- 
ment, and Control in Science and Industry, vol. 1, Reinhold 
Publishing Corporation, New York, 1965, pp. 465-480. 

2. J. W. Wilkerson, "Airborne Oceanography," Geo-Marine 

Technology, vol. 2, No. 8, Sept. 1966, pp. 9-16. 

3. J. D. McFadden, "Sea Surface Temperatures in the Wake of 

Hurricane Betsy (1965)," Monthly Weather Review, vol. 95, 
No. 5, May 1967, pp. 299-302. 



[Received July 11, 1967] 



279-151 O - 67 - 9 



Reprinted from JOURNAL OF GEOPHYSICAL RESEARCH 
Vol. 72 No. k The American Geophysical Union 

Journal of 

Geophysical Research 



Volume 72 



February 15, 1967 



No. 4 



Climatological Significance of Albedo in Central Canada 

James D. McFadden 1 and Robert A. Ragotzkie 

Department of Meteorology, University of Wisconsin, Madison 

Between 1961 and 1965, short wavelength albedo data were collected on a number of aerial 
reconnaissance flights made over the north-central portion of the United States and central 
Canada from Wisconsin to the Arctic Ocean during periods of lake freezing and thawing. These 
data show that there is very little horizontal variation in the albedo of the tundra in the 
summer, when lakes are free of ice, and in the winter, when they are frozen and the region is 
snow covered. Large horizontal variations of albedo occur in the tundra when lakes are frozen 
but there is no snow, and in the boreal forest region when the lakes are frozen and snow 
covered. The albedo values obtained over the tundra region were used to estimate the change 
in the heat balance for the land surface for the period of rapid snow disappearance in June 
1963. This estimate indicates that the sensible heat transfer to the atmosphere was sufficient 
to heat the lower 1000 meters of air at a rate of 1.6°C per day for this period, a value that 
agrees quite well with actual observations. 



Introduction 

Surface albedo, which may be denned as the 
ratio of reflected to incident solar radiation at 
the earth's surface, is important in any climatic 
study, because the portion of the incident solar 
radiation that is not reflected by the surface is 
absorbed as heat that becomes available for 
heating the lower atmosphere or for evaporat- 
ing water. The horizontal variations and the 
seasonal changes of albedo over large areas are 
important to air mass modification and regional 
climate studies. These variations and changes can 
be estimated from aerial measurements of al- 
bedo. Adequate studies on the feasibility and 
suitability of using aircraft for surface albedo 
measurements have been made by such investi- 
gators as Fritz [1948], Bauer and Dutton [1960, 
1962], Dutton [1962], Rung et al. [1964], and 
Hanson and Viebrock [1964]. The reader is di- 
rected to these papers for detailed discussions 
of this subject. 



1 Now at the Sea Air Interaction Laboratory, 
ESSA, Silver Spring, Maryland. 



Between 1961 and 1965, albedo data were 
collected on a number of aerial reconnaissance 
flights made over north-central United States 
and central Canada from Wisconsin to the Arctic 
Ocean during periods of lake freezing and thaw- 
ing. These data were collected in conjunction 
with a study on the interrelationship of lake ice 
and climate [McFadden, 1965], and therefore 
the main emphasis of this paper will be on the 
effects of lakes and snow cover on albedo in the 
tundra and boreal forest regions of central 
Canada, and the climatological significance of 
these effects for these particular regions. Al- 
bedo values from the northern hardwood-conifer 
forest and farm land region of the United States 
are included for purposes of comparison. 

Method 

A U. S. Navy P2V Neptune patrol aircraft 
was used as the aerial platform from which 
incident and reflected short-wave radiation used 
to compute albedo were measured. The plane 
and its crew were provided by the Service Test 
Division of the Naval Air Test Center, Patuxent 



1135 



1136 



McFADDEN AND RAGOTZKIE 



River, Maryland, through the Office of Naval 
Research. Ideally, the data were collected at 
1000 feet above the terrain, although on occa- 
sion low stratus clouds forced the aircraft below 
this level in order for the pilot to maintain 
visual contact with the ground. 

Two Kipp and Zonen solarimeters were 
mounted level for flight on the upper and 
lower surfaces of the fuselage of the aft section 
of the aircraft. The construction of the upper 
and lower surfaces of the fuselage is essentially 
uninterrupted except for the vertical stabilizer, 
thus providing both sensors almost completely 
unobstructed fields of view. The solarimeters 
give an output proportional to the incident 
short-wave radiation of about 8 mv/ly/min. 
They have a time constant of about 2.0 sec and 
are accurate within an error of 3% [Bener, 
1951]. The outputs were recorded on a Minne- 
apolis-Honeywell Brown 12-point recorder. Each 
of the outputs from the top and bottom sensors 
was recorded alternately on this recorder every 
2 sec. 

The albedo records were analyzed in the fol- 
lowing manner. The record of each flight was 
first stratified according to terrain type, snow 
cover, time of day, and cloud cover as recorded 
by 16 mm movies, still pictures, and notes of 
existing conditions made at frequent intervals 



by the observer during each flight. After the 
sectioning of the record was complete, values 
of the upper and lower solarimeters were read 
at %-min intervals within each section. Albedo 
in per cent, which is the ratio of reflected to 
incident solar radiation times 100, was com- 
puted for the individual readings. The mean, 
standard deviation, and relative variance (co- 
efficient of variability) for the albedo of each 
section were also computed. 

It should be pointed out at this time that the 
values given in this paper are hemispheric al- 
bedo and somewhat different from the beam 
albedo values presented in the paper by Kung 
et al. [1964]. The significance of this difference, 
as far as the climatological aspects of this paper 
are concerned will be examined later, but dif- 
ference in the mechanics of the two methods of 
obtaining albedo from aircraft will be discussed 
here. 

Beam albedo is calculated from the output of 
an upward-facing hemisphere radiometer and a 
radiometer with a downward-facing parabolic 
mirror that intercepts energy from a small area 
within a 4° beam width and focuses this energy 
on the radiometer. Hemispheric albedo, on the 
other hand, is determined from the records from 
the same type of upward-facing radiometer and 
a down-facing solarimeter that has a full 2-ir ster. 



TABLE 1. Representative Albedo Values for Various Regions 



Terrain 



Lakes 



Standard Relative 

Mean, Deviation, Range, Variance, 
Snow Cover % % % % 



Sky 



Tundra 


Frozen 


Snow 


89.0 


2.98 


84.0-92.0 


3.4 


Clear 


Tundra 


Frozen 


Snow 


77.7 


3.45 


70.5-83.2 


4.4 


Stratus 


Tundra 


Partly frozen 


No snow 


24.9 


8.82 


15.2-47.1 


35.4 


Clear 


Tundra 


Unfrozen 


No snow 


10.8 


1.14 


7.9-12.4 


10.6 


Clear 


Tundra 


None 


No snow 


14.8 


0.95 


13.5-15.6 


6.4 


Clear 


Tundra 


None 


No snow 


14.9 


1.14 


13.8-16.5 


7.7 


Clear 


Forests 


Frozen 


Snow 


48.0 


1.14 


30.3-63.2 


23.7 


Clear 


Forests 


Frozen 


Snow 


46.9 


0.97 


37.9-68.2 


20.7 


Clear 


Forests 


Partly frozen 


Snow 


34.5 


8.00 


22.7-54.5 


23.2 


As 


Forests 


Partly frozen 


No snow 


26.7 


3.80 


11.1-29.5 


14.2 


Clear-Hazy 


Forests 


Partly frozen 


No snow 


16.9 


2.00 


10.7-20.2 


11.9 


As 


Forests 


None 


Light snow 


18.2 


3.00 


13.0-26.0 


16.7 


Clear-Hazy 


Forests 


None 


No snow 


14.9 


2.00 


12.7-19.0 


13.5 


Clear-Hazy 


Fields, woods 


None 


Snow 


43.8 


4.00 


31.2-48.3 


9.2 


Clear-Hazy 


Farms 


None 


None 


22.1 


3.8 


13.4-26.4 


17.2 


Clear-Hazy 


Farms 


None 


None 


18.9 


0.8 


17.7-19.7 


4.5 


Clear-Hazy 


Farms, woods, 
















and bogs 


None 


None 


18.6 


2.5 


13.5-22.7 


13.7 


Clear-Hazy 


Plowed fields 


None 


None 


12.3 


1.6 


11.1-14.2 


13.3 


Clear-Hazy 



CLIMATOLOGICAL SIGNIFICANCE OF ALBEDO 



1137 





100 


r ' < 














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- 


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LAKE 
CONDITION 


FROZEN 


PARTLY 
FROZEN 


UNFROZEN 


NO LAKES 


















COVER 




SNOW 




NO SNOW 







Fig. 1. Albedo means and ranges for tundra 
region. Sky condition for each set of measure- 
ments is also shown. 



field of view. At an altitude of 500 feet the beam 
albedo system will instantaneously sample an 
area 35 feet in diameter, while the hemisphere 
system samples over the entire solid angle. 

In a general way, values from the two dif- 
ferent systems can be compared. Bauer and 
Dutton [1962] and Dutton [1962] observed 
that for a fresh layer of snow on a lake, which 
they assumed to be a homogeneous and isotropic 
surface, the measured hemispheric and beam 
albedo values were in agreement and that a 
calibration factor of 1.294 for the beam reflector 
incorporated all deviations from the ideal para- 
bolic reflector. Further, they showed that for 
various terrain surfaces, excluding water, with- 
out snow cover the ratio of hemispheric albedo 
to (beam albedo X 1.294) was very close to 
unity. One should expect, then, that the albedo 
values reported herein for areas with no snow 
and for a snow covered tundra would be in 
agreement with beam albedo values, incorporat- 
ing the calibration factor above. A comparison 
of beam albedo values obtained by Kung et al. 
[1964] and hemispheric values obtained by the 
authors for similar type terrain in southern 
Manitoba, under like conditions and at approxi- 
mately the same date, showed that the values 
were almost equal after the calibration correc- 
tion was made. The beam albedo averages for 
swamps, fields, and wooded farms in this area 
ranged from 12 to 14%, whereas the corrected 





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40 








at 
< 


< 

as 




- 












i— 


< 












T 


u 


o 














i 


1— 

< 


T 


13 
as 




20 








i 


! 












-L 






LAKE 
CONDITION 


FROZEN 


PARTLY FROZEN 


NO LAKES 


SNOW 
COVER 


SNOW 


NO SNOW 


LIGHT 
SNOW 


NO 
SNOW 



Fig. 2. Albedo means and ranges for boreal 
forest region. Sky condition for each set of meas- 
urements is also shown. 

hemispheric averages ranged from 11.8 to 14.4%. 
The uncorrected values ranged from 15.2 to 
18.6%. 

Results 

Representative sections from the albedo rec- 
ords obtained on various flights and covering 
horizontal distances of 15 to 50 miles over the 



100 

80 

O 

2 60 

CO 

< 

40 

20 


( 


1 


SXY CONDITION 

1 - I 


- CLEAR 
BUT HAZY 

5 


TERRAIN 


FARMS 
WOODS 


FARMS 


FARMS, 
WOODS, 
AND BOGS 


PLOWED 
FIELDS 


SNOW 
COVER 


SNOW 


NO SNOW 



Fig. 3. Albedo means and ranges for northern 
hardwood-conifer forest and farmland mixture. 



1138 



McFADDEN AND RAGOTZKIE 



TABLE 2. Albedo Means, Standard Deviations, and Ranges 
in Per Cent for Various Surfaces 



Date 



Time, 
CST 1 



Area Description 



Standard 
Mean Deviation 



Range 



July 13, 1962 1714 Kazan River, tundra, clear sky, altitude 

2200 ft 2 
1800 Tundra and lakes, clear sky 
1830 Tundra and lakes, clear sky, altitude 2000 ft 
1845 Tundra and lakes, altitude 2000 ft 
July 15, 1962 1103 Hudson Bay water (no ice) 

1120 Fog banks over Hudson Bay 

1130 Fog banks over Hudson Bay 

1130 Ice flow on Hudson Bay 
1130-1200 Marshy tundra and lakes, coastal lowlands, 
high percentage of lakes 
1200 Tundra and small lakes, stratus 3 
1210 Tundra and lakes, 70% lakes mostly ice 

covered; thin stratus 
1220 Tundra and lakes, some ice on lakes, 

40-50% lakes, 63°30'N, thin stratus 
1330 White Hills Lake, ice covered 10/10 cirrus 
1330 Tundra and few lakes, north of Rossby Lake 
1445 Chantrey inlet, floating ice 

1450 Chantrey inlet, light colored water 
1530 Sherman inlet, ice; Alto-stratus clouds 

3500 ft 
1530 Sherman inlet, ice, 3500 ft Alto-stratus 
1730 Tundra and lakes, 3500 ft 
1830 Dabawnt Lake, ice; stratus 
1920 Tundra and lakes, near Ennadai 
1950 Tundra east of Ennadai 
May 22, 1963 1100-1200 Spruce trees, no snow, frozen lakes, darkish 

ice, bogs, clear sky 
1300-1345 Spruce forest, lakes, no ice, bogs, altitude 
8000 ft 
June 9, 1963 1215 Kasba Lake, ice covered, stratus, thinning, 

heavy snow cover 
1230 Ennadai Lake, ice cover, stratus, thinning, 

heavy snow cover 
1325 Large lake surrounded by rocky tundra, 

ice, no snow, clear 
1420 Spruce forest, heavy snow cover, lakes open, 
stratus thinning 
June 12, 1963 0835-0922 North of Winnipeg, farms and marshes, no 

snow, stratus, var. thickness 
0922-0941 Lake Winnipeg, stratus-var. thickness 
1015-1030 55°40'N, 98°W, spruce forest, no snow 
1225-1245 Mostly trees, some bogs (may be tundra), 

lakes open, stratus 
1250-1308 (Mostly trees) mixed forest-tundra, lakes 

partly frozen, stratus 
1308-1508 (Mostly trees) mixed forest-tundra, lakes 

partly frozen, thinning stratus 
1508-1528 Marsh and bogs, east of Lake Winnipeg 
stratus 
June 14, 1963 0835-0853 Bog and marshy area NNW of Winnipeg, 

some scattered lakes, clear 
0855-0915 Bog and marshy area NNW of Winnipeg, 

some scattered lakes, clear 
0933-0937 Lake Winnipegosis, clear 
0941-0945 Cedar Lake 53°15'N, 100°W, clear 



17.1 


1.82 


11.8-21.3 


19.9 


1.24 


18.0-21.8 


19.1 


1.00 


18.3-19.6 


20.4 


1.26 


17.4-23.7 


4.9 


0.616 


4.6-5.1 


9.0 


0.436 


7.7-10.1 


10.2 


0.995 


8.5-11.4 


28.7 


3.94 


24.5-33.1 


10.8 


1.14 


7.9-12.4 


16.1 


2.28 


12.3-19.3 


16.7 


2.42 


13.5-21.4 


15.4 


2.24 


11.5-20.0 


27.5 


0.773 


26.8-28.8 


14.9 


1.14 


13.8-16.5 


21.7 


1.60 


18.3-23.8 


13.4 


0.894 


11.3-15.3 


25.8 


2.10 


23.4-29.0 


25.1 


2.09 


20.6-27.7 


16.0 


0.949 


12.6-19.1 


31.7 


0.671 


29.7-33.4 


20.0 


2.561 


16.4-25.6 


18.5 


1.76 


13.6-22.7 


12.3 


1.31 


10.2-18.9 


10.4 


1.23 


7.2-12.2 


60.1 


3.16 


57.5-63.0 


63.7 


3.85 


58.6-70.8 


29.4 


7.5 


17.7-38.7 


23.0 


3.38 


16.7-28.4 


17.8 


1.55 


16.2-20.3 


11.1 


1.18 


9.7-12.4 


10.5 


1.45 


7.6-11.8 


14.2 


1.38 


11.3-17.0 


13.3 


2.09 


8.6-16.1 


18.2 


2.72 


14.5-29.4 


17.2 


2.72 


12.5-27.2 


15.2 


1.23 


11.0-16.9 


14.2 


1.38 


12.6-15.7 


8.0 


0.77 


7.8-8.5 


7.3 


0.84 


6.8-8.1 



CLIMATOLOGICAL SIGNIFICANCE OF ALBEDO 
TABLE 2 (Continued) 



1139 



Date 



Time, 
CSTi 



Area Description 



Standard 
Mean Deviation Range 



1023-1029 

1334-1344 

June 15, 1963 0905-0945 

June 29, 1963 0900-0920 

0940 

0950 

1035 

1145-1200 

1200-1245 

1245-1255 
1325-1410 
1420 
July 1, 1963 1108-1112 

1115-1121 

1150-1210 

1225-1238 



1245 
1630 

Oct. 15, 1963 1407-1447 



Forests, lakes, and some open areas near 

Cranberry Portage 
Dubawnt Lake, ice, light colored, heavy 

stratus 
Cultivated fields South of Winnipeg, 

prairies, no lakes, clear sky 
Tundra, open lakes, clear sky 
Tundra, open lakes, clear sky 
Tundra, open lakes, clear sky 
Lakes and Tundra 
McLeod Bay, open but with some small ice 

floes, clear 
Rocky tundra and lakes north of Great 

Slave Lake, most lakes open, some 

partly frozen 
Rocky tundra north of Great Slave Lake, 

some lakes open, more frozen, clear 
Mostly tundra, some small lakes and some 

ice, clear 
Lakes with fairly dark ice, tundra small 

lakes open, stratus 
Mostly light brown and green tundra, very 

little water, just south of Aberdeen Lake, 

clear 
Mostly light brown and green tundra, but 

more lakes and ice. Just north of Aber- 
deen Lake, clear 
Greenish tundra with some sandy areas, 

lakes, 0.5 ice north of Gary L., clear 

(some cumulus) 
67°25'N, 97°-98°W. Dark brown tundra, 

lakes, partly open, some light ice, some 

snow banks 
Sea ice in Chantrey Inlet, clear 
Hudson Bay, open waters, under thin 

stratus near Churchill 
63°30' to 64°30'N, tundra, frozen lakes, 

snow cover, under stratus 



15.2 
53.1 

17.7 

12.7 
12.7 
13.1 
11.6 

6.6 



1.95 

5.93 

1.32 
1.34 
1.70 
1.72 
1.79 

0.028 



12.7-18.0 
41.8-64.2 

15.2-21.1 
9.4-14.8 
8.2-15.2 

10.1-15.3 
8.0-14.8 

6.1-8.7 



14.6 


2.57 


8.9-28.7 


24.9 


8.82 


15.2-47.1 


16.2 


1.10 


14.1-20.4 


32.7 


9.54 


20.1-48.7 


14.8 


0.95 


13.5-15.6 


14.9 


2.38 


13.0-20.2 


16.4 


4.29 


12.0-31.6 


16.8 


2.72 


13.2-25.7 


47.5 


1.84 


45.5-49.8 


10.9 


0.539 


9.7-11.6 


77.7 


3.45 


70.5-83.2 


ay be estimated by (3 X time 



1 Where time intervals are given distance of transect in nautical miles may be estimated by 
interval in minutes). 

2 All values obtained at aircraft height of 1000 ft or lower except where indicated. 

3 Aircraft below cloud level in all cases. 



thrqe regions mentioned above were selected. 
The mean, standard deviation, relative variance, 
and range of the albedo for each of these sec- 
tions are given in Table 1 and shown graphically 
in Figures 1, 2, and 3. Additional values of 
albedo for various regions are presented in 
Table 2. Relative variance, or coefficient of vari- 
ability (see Steel and Tome [1960] and Kung 
et al. [1964]), which is the ratio of standard 
deviation to mean in per cent, expresses gen- 



erally the variation of the reflectivity caused by 
the heterogeneity of the surface. 

The tundra region of Canada, because of the 
general absence of trees, exhibits the highest 
seasonal range of albedo of the three major 
areas studied (see Figure 1). The numerous 
lakes in this region do not, however, have a 
large effect on the horizontal variation of albedo 
in the winter or the summer seasons. During the 
winter when all lakes are frozen, the surface 



1140 



McFADDEN AND RAGOTZKIE 



can be considered continental, and, with a snow 
cover, it has a high albedo with a low coefficient 
of variability. During the summer the albedo of 
the tundra is low enough so that the addition 
of lakes causes only a slight decrease in the 
mean reflectivity of the surface. However, in 
spring and autumn, when the lakes are partially 
frozen with no snow cover on the ground, there 
is a pronounced lake effect on the albedo. During 
the spring and autumn, the albedo is extremely 
variable, and the standard deviation and rela- 
tive variance are very high. 

In the boreal forest region (Figure 2) the 
seasonal changes of albedo are not as great as 
in the tundra, but the lake effect is larger as 
indicated by wider ranges of values and gen- 
erally higher coefficients of variability. Consid- 
ering the nature of the terrain this is under- 
standable. The crowns of the trees do not 
support the generally dry and powdery snow, and 
the forest appears dark during both winter and 
summer, particularly when viewed from the di- 
rection parallel with the incident solar radia- 
tion. Interspersed throughout the forest are 
numerous lakes and bogs. In the winter when 



these are frozen and snow covered, they appear 
as light areas, raising the average albedo of the 
region by a factor of 2 or more compared with 
forest areas without lakes and bogs (Figure 4). 
As mentioned earlier, the method of obtain- 
ing albedo information for an essentially uni- 
form or isotropic surface is not too critical. For 
a snow covered forest that is clearly anisotropic, 
as Figure 4 shows, careful consideration must be 
given to whether the values of reflected radia- 
tion were obtained with a beam or a hemi- 
speric radiometer. The reflectivity of a snow 
covered forest of the type observed in central 
Canada is much higher when viewed from above 
than from an angle, because more of the lighter 
snow covered ground is visible. A beam solarim- 
eter, then, would probably give higher reflected 
values over this region than a hemisphere de- 
vice, because the hemisphere instrument also 
'sees' the darker ground at an angle. Actually, 
the surface might absorb more energy than 
either albedo method would indicate because 
the hemispheric solarimeter also receives most 
of its energy from the vertical. When consider- 
ing the amount of energy absorbed by the boreal 




Fig. 4. View of snow covered terrain in boreal forest region. 



CLIMATOLOGICAL SIGNIFICANCE OF ALBEDO 



1141 



forest and by the tundra in the autumn and 
spring, the albedo measurements obtained by 
either method, and in particular by the beam 
method, might tend to indicate smaller absorbed 
energy differences between the two regions than 
actually exist. 

Using values of direct and diffuse solar radia- 
tion from Bernhardt and Phillips [1958], an 
observed mean surface albedo value under a 
stratus cloud condition for diffuse radiation, and 
a computed estimate of direct radiation, based 
on a knowledge of the albedo of the trees and 
snow covered lakes and bogs, it is possible to 
conclude what the true albedo of an area in a 
boreal forest region similar to that shown in 
Figure 4 would possibly be in early November 
at 55°N latitude under a cloudless sky. An ob- 
served value of 34.5% (Table 1) was used in 
the estimate for the albedo of this area for 
diffuse radiation. For the direct radiation a 
value of about 28% was computed, using albedo 
values of 12% for the conifers and 77% for the 
snow covered open areas, and a land cover 
ratio of 3 to 1 in favor of the trees. At that 
time of year and for that location, half the 
radiation incident on the earth's surface is direct 
and half is diffuse. Thus, the estimated true 
albedo would be approximately 31%, indicating 
that the measured mean values (Table 1) are 
possibly too high by a factor of about 35%. 

Albedo values obtained from the northern 
hardwood-conifer forest and farm land mixture 
region (Figure 3) are included primarily for 
comparison with values obtained over similar 
areas by Bauer and Dutton [1960] and Kung 
et al.. [1964]. Kung et al., for example, give 
November albedo values (converted by means 
of the ^eam-to-hemispheric calibration factor of 
1.294) for Wisconsin farmland of approximately 
18 to 22%, which compares favorably with 
values given in Table 1, also obtained during 
November. 

Climatological Significance 

Of significance to the meteorologist are the 
effects that seasonal changes of albedo have on 
regional climate and general circulation patterns. 
For example, Bryson and Lahey [1958] have 
suggested that a rapid and drastic change of the 
albedo of the tundra in June might trigger the 
change from one natural season to another. By 
using albedo values given above, snow observa- 



TABLE 3. Effect of Observed Albedo on Effective 
Solar Radiation for Tundra Region 





June 1 


June 21 


Albedo of lnnd, % 


83 


15 


Albedo of lakes (15% of 






surface), % 


83 


40 


Solar radiation at surface 






under average cloud con- 






ditions (estimated from 






Bernhardt and Philipps 






[1958]), ly/day 


352.8 


446.4 


Radiation absorbed per unit 






area, ly/day 






Land 


60.0 


379.4 


Lakes 


60.0 


267.8 


Land-lake combination 


60.0 


362.6 



tions from Operation Breakup 1963 \McFadden, 
1965], and solar radiation values estimated from 
the results of Bernhardt and Phillips [1958], 
it is possible to estimate the change in absorbed 
solar radiation between snow and no snow con- 
ditions. The results shown in Table 3 were com- 
puted for the tundra area of northern Canada 
lying south of the sixty-eighth parallel and west 
of Hudson Bay. 

On the flight of May 22, 1963, the snow line 
was observed some 250 miles south of the forest- 
tundra border, and on the flight of June 14, no 
snow was observed as far north as 64°N, or 450 
miles north of the May 22 snow line position. 
No snow was observed on the July 1 flight to 
the Arctic Ocean. It is reasonable to assume 
from these three observations that the tundra 
was still completely snow covered as late as 
June 1 and probably snow free no later than 
June 21. During this 3-week period the albedo 
of the tundra dropped from an average of 
approximately 83% to about 20% (15% for 
the land surface and about 40% for the partly 
open lakes that constitute up to 15% of the 
tundra surface). This decrease in the reflectivity 
of the surface plus the increase in incident radia- 
tion at the surface between June 1 and 21 re- 
sulted in a 600% increase in the absorbed radia- 
tion of from 60 to 363 ly/day during this period. 

Whether this sudden and drastic change of 
albedo actually served as a triggering mecha- 
nism for the atmosphere will have to await 
further study, but it seems plausible that this 
tremendous increase of energy occurring sud- 
denly and at about the same time in all the 



1142 



McFADDEN AND RAGOTZKIE 



TABLE 4. Heat Balance Estimate for 
Tundra Region 1963, ly/day 

June 1 June 21 

Incoming solar radiation 352 . 8 446 . 4 
Reflected solar radiation —292.8 —66.9 
Effective long wave radiation — 131 . — 132 . 5 
Net radiation -71.0 247.0 
Heat storage (land) 2.5 
Heat required to melt perma- 
frost (0.5 cm/day) 36.0 
Heat for evaporation (latent)* —160.4 
Sensible heat* -48.1 

* Using Bryson and Kuhn's Bowen ratio value 
(0.30). 

tundra regions of the northern hemisphere 
should produce a noticeable effect. 

To obtain some idea of the partitioning of 
this energy absorbed by the tundra and the 
amount available as sensible and latent heat, 
the heat balance for the area was estimated 
(Table 4). 

The equation for estimating the net radiation 
at the tundra surface is given by 



R N = R r + Rr + Ri 



where 



R N = net radiation. 
Ri = incoming short-wave radiation. 
R R = reflected short-wave radiation. 
R Lelt = effective long-wave radiation. 

The values of incoming solar radiation and 
albedo are the same as given in Table 3, and the 
formula for computing effective long-wave ra- 
diation is that of Budyko [1958]. 

The heat balance equation for estimating 
sensible and latent heat transfer over the land 
surface is given by 



S+M = R V +Q + E 



where 



S — heat stored in the soil. 
M = permafrost melt (estimated at 0.5 cm/ 

day from in situ measurements). 
Q = sensible heat. 
E = heat for evaporation (latent heat). 

For estimating the storage and melting terms 
of the heat budget equation, Larsen's [1965] 
values for permafrost depths and soil tempera- 



tures in tussock muskeg material for the period 
June 1-21, 1963, near Ennadai, Northwest 
Territories, were used. The July Bowen ratio 
estimate (0.30) of Bryson and Kuhn [1962] 
for the region from Norman Wells, Northwest 
Territories, to Fort Smith, Alberta, was used for 
determining the sensible and latent heat terms 
because a ratio estimate for June was not avail- 
able. 

Applying the estimated value for sensible 
heat transfer to the atmosphere, 48.1 ly/day, 
to a column of air 1000 meters in height and 
with a mean temperature of 0°C gives a heating 
rate of approximately 1.6°C per day. This heat- 
ing rate does not appear to be unrealistic. From 
radiosonde data obtained at Baker Lake on 
June 20, 1963, the average temperature increase 
between 0600 and 1800 hours CST in the lower 
1000 meters was computed to be 1.3°C. An 
average temperature increase of 1.85°C per day 
for this layer was also computed for the period 
between 1800 hours on June 17 and 1800 hours 
on June 21. This increase agrees quite well with 
the results in Table 4. Winds at this station 
during this period were very light to calm and 
more northerly in frequency. 

Conclusion 

Whereas the major change in the albedo of 
central Canada was a result of the presence or 
absence of snow, the effects of lakes were strik- 
ingly different in the tundra and boreal forest 
regions. Lakes caused very little horizontal vari- 
ation in either the summer or winter in the 
tundra, but they produced a large effect during 
the transition months of fall and spring. In the 
boreal forest region lakes also had little effect 
on the range of albedo in the summer. Small 
horizontal range was noted during the fall as 
lakes were freezing and prior to the first snow. 
The largest variation of albedo was obtained 
over this region in the winter, when the lakes 
were frozen and there was a good snow cover 
on the ground. A large range was also noted in 
the spring after the snow had melted but before 
the lakes had thawed. 

The rapid disappearance of snow from the 
tundra observed in June 1963 caused an esti- 
mated 600% increase in the absorbed radiation 
at the surface. Whether this rather sudden and 
drastic change in absorbed radiation occurring 
over the entire tundra region had any effect on 



CLIMATOLOGICAL SIGNIFICANCE OF ALBEDO 



1143 



the general circulation pattern must await fur- 
ther study. The estimated heating of 1000 
meters of atmosphere by an average of 1.6°C 
per day during this period agrees fairly well 
with radiosonde observations at Baker Lake, 
Northwest Territories. 

Acknowledgments. The authors are grateful to 
Professors Bryson and Horn for their advice and 
criticism, to the U. S. Navy, in particular the 
officers and crew of P2V 128362, and to Messrs. 
Bernhard Lettau, David Drury, James Peterson, 
Wayne Wendland, Dennis Finke, Ben Bullock, and 
Robert Knollenberg for their efforts toward col- 
lecting and reducing the data. 

This research was supported by the Geography 
Branch, Office of Naval Research Contract Nonr 
1202 (07) with the Department of Meteorology, 
University of Wisconsin. 

References 

Bauer, K. G., and J. A. Dutton, Flight investiga- 
tions of surface albedo, Tech. Rept. 2, Contract 
DA-36-039-SC-S0282, Department of Meteorol- 
ogy, University of Wisconsin, Madison, 1960. 

Bauer, K. G., and J. A. Dutton, Albedo variations 
measured from an airplane over several types of 
surface, J. Geophys. Res., 67(6), 2367-2376, 1962. 

Bener, P., Untersuchung iiber die Virkungsweise 
des Solarigraphen Moll-Gorezynski, Arch. Mete- 
orol., Geophys., Bioklimatol., Ser. B, 2, 188-249, 
1951. 

Bernhardt, F., and H. Phillips, Die Raumliche 
und Zeitliche Verteilung der Einstrahlung, der 
Ausstrahlung und der Strahlungsbilanz im 
Meeresniveau, 1, Die Einstrahlung, Abhandl. 
des Meteor ologischen Hydrologischen, Dienstes 
der Deutschen Demokratischen Republik, NR. 
45, Akademie-Verlag, Berlin, 1958. 



Bryson, R. A., and P. M. Kuhn, Some regional 
heat budget values for northern Canada, Geo- 
graph. Bull. 17, 57-66, 1962. 

Bryson, R. A., and J. F. Lahey, The march of the 
seasons, Final Rept. Department of Meteorol- 
ogy, University of Wisconsin, Madison, Contract 
AF 19-(604)-922, 1958. 

Budyko, M. I., The heat balance of the earth's 
surface, (translated from Russian), Office of 
Technical Services, U. S. Department of Com- 
merce, Washington, D. C, 1958. 

Dutton, J. A., An addition to the paper 'Albedo 
variations measured from an airplane over sev- 
eral types of surface,' J. Geophys. Res., 67(13), 
5365-5366, 1962. 

Fritz, S., The albedo of the ground and the at- 
mosphere, Bull. Am. Meteorol. Soc, 29, 303, 
1948. 

Hanson, K. J., and H. J. Viebrock, Albedo meas- 
urements over the northeastern United States, 
Monthly Weather Rev., 92(b), 223-234, 1964. 

Kung, E. C, R. A. Bryson, and D. H. Lenschow, 
Study of a continental surface albedo on the 
basis of flight measurements and structure of the 
earth's surface cover over North America, 
Monthly Weather Rev., 92(12), 543-564, 1964. 

Larsen, J. A'., The vegetation of the Ennadai Lake 
area, N.W.T., Studies in subarctic and arctic 
bioclimatology, Ecological Monographs, 35, 37- 
39, 1965. 

McFadden, J. D., The interrelationship of lake 
ice and climate in central Canada, Tech. Rept. 
20, ONR Contract Nonr 1202(07), Department 
of Meteorology, University of Wisconsin, Madi- 
son, 1965. 

Steel, R. G. D., and J. T. Torrie, Principles and 
Procedures of Statistics, McGraw-Hill Book Co., 
New York, 1960. 

(Received August 25, 1966.) 






Reprinted from JOURNAL OF GEOPHYSICAL RESEARCH 
Vol. 7 2 , No. 2 The American Geophysical Union 



8 



Journal of Geophysical Research 



Vol. 72, No. 2 



January 15, 1967 



Dissolved Chemical Substances in Compacting Marine Sediments 1 

William A. Anikouchine 

Joint Oceano graphic Research Group 
Institute for Oceanography, ESSA 
University of Washington, Seattle 

A mathematical description of the distribution of a dissolved chemical species in inter- 
stitial water of clayey marine sediments is obtained by applying the equation of the distribu- 
tion of a scalar variable to a constantly accumulating column of marine sediments. An equa- 
tion describing compaction, and hence interstitial water velocity, is obtained empirically 
from porosity data. When the space coordinates are transformed to the moving sediment- 
water interface, the advection term vanishes and a simple equation involving diffusion, re- 
action, and local change describes the distribution of chemical species dissolved in interstitial 
water. This equation is solved to obtain a steady-state distribution of dissolved silicate and 
the diffusive flux of dissolved manganese across the sediment-water interface, and agree- 
ment between theoretical predictions and empirical data is found. The validity of assump- 
tions used in developing the mathematical model is discussed. 



Introduction 

Several mathematical models have been de- 
vised to describe the depth distribution of con- 
centration of various chemical species dissolved 
in the interstitial water of marine sediments 
[Koczy, 1961; Goldberg and Koide, 1963; 
Berner, 1964, 1966]. These models include the 
effects of diffusion, reaction, and moving space 
coordinates, but no provision has been made 
for the movement of interstitial water caused 
by compaction of the sediments. This provision 
is included in the model described in this 
paper. 

The procedure used is (1) to state a dis- 
tribution equation in terms of coordinates fixed 
with respect to a fixed basement, (2) to derive 
an advection term from an empirical porosity- 
depth relationship, (3) to transform to moving 
coordinates to include the effects of sediment 
accumulation, (4) to solve the resulting equa- 
tion under steady-state conditions, and (5) to 
compare the solution with data on interstitial 
water. 

Development of the Model 

The distribution of dissolved chemical spe- 
cies in interstitial water is dependent upon 



1 Contribution 398 from the Department of 
Oceanography, University of Washington; JORG 
contribution 6. 



diffusion, advection, and reaction within the 
interstitial water (or between the interstitial 
solution and sediment grains). The dependence 
is expressed by the equation for local change 
dc/dt of concentration: 

The second-order term describes Fickian dif- 
fusion with a constant coefficient of diffusivity, 
D. Advection at a point h above the fixed 
basement is described by the product of- v K , the 
velocity of expelled interstitial water, and dc/ 
dh, the concentration gradient. The reaction 
term is the product of the first-order reaction 
rate constant fo and the extent-of-completion 
parameter (c — c r ), which is the difference 
between c, the concentration at h, and the 
final or saturation concentration c,. 

The combined effects of sediment accumu- 
lation and compaction of the sediments cause 
the sediment-water interface to move upward 
from the fixed basement. In a hypothetical case 
(Figure 1) the interface moves upward at a 
constant rate K after sufficient time has 
elapsed. Experimental evidence [Long, 1961] 
suggests that clayey sediments behave simi- 
larly. Because sediment properties are normally 
measured relative to the sediment-water inter- 
face, the space coordinate of (1) is transformed 
to move with the interface by substituting 



505 



506 



WILLIAM A. ANIKOUCHINE 




ZONE OF 
.COMPACTION 
MOVING UPWARD 
THROUGH SPACE 
AT A CONSTANT 
RATE, K 






FIXED BASEMENT 
AT h = 



V 



COMPACTION IS 
ESSENTIALLY 
COMPLETE IN 
THIS REGION 



' i > —t £ 



* '•" I"" '■' 



_l I I I I I I L 



U AFTER THIS TIME, THE 

r*^ INTERFACE BUILDS UPWARD AT 
ALMOST A CONSTANT RATE, K 

Fig. 1. Compaction behavior of a hypothetical column of sediment. Solid lines are tra- 
jectories of individual sediment particles. Vertical distances between adjacent dotted curves 
represent the sediment porosity at that time and place. 



z = h - Kt (2) 

t = T (3) 

The change with time T of concentration c at 
a depth z below the interface is described by 
the transformed equation : 

dc dc d 2 c dc . s ( . 

w- K Tz =D -&- v 7z- k ^- Cf) (4) 

The interstitial water velocity (with respect 
to the interface v) is determined by consider- 
ing that the sediment compacts so that the 
profile of porosity n with depth z remains un- 
changed as indicated in Figure 1. Porosity is 



piaue. 

assumed to vary with depth as follows [Athy, 
1930] : 

n = n exp —(mz) (5) 

The porosity at the interface n* and the com- 
paction factor m are derived empirically. 
The continuity equation 



dn 
dt 



ds 
dz 



(6) 



relates the time rate of change of porosity and 
the gradient of superficial velocity s. The su- 
perficial velocity is the flow of interstitial water 
per unit cross-sectional area of sediment. The 



DISSOLVED CHEMICALS IN MARINE SEDIMENTS 



507 



rate of change is found, from (2) and (5), to 
be 



dn 
dt 



— mKn exp (mz) 



(7) 



Substituting (6) and integrating yields 



s = Kn exp (mz) + d (8) 

The constant of integration Cj is evaluated by 
assuming that the sediments are infinitely thick 
and are totally compacted at depth, so that 

s — > z — > - oo (9) 

Under these conditions, Ci is zero and 

s = Kn exp (mz) (10) 

The interstitial water velocity v and the super- 
ficial velocity s are related by the equation 



v = s/n 



(11) 



Hence (10) becomes 



v = K (12) 

and the distribution equation (4) becomes 

£-*§-**-«) 03) 

The advection term disappears because move- 
ment of water toward the interface is count- 
ered by interface movement during sediment 
accumulation. 

Equation 13 is solved by assuming that a 
steady state exists and that diffusion balances 
reaction. The boundary conditions are 



C—*C t g — > — oo 


(14) 


C = Co 2=0 


(15) 


and the solution is 




f^f- = exp [z(h/D) 1/2 ] 

C — Cf 


(16) 


Discussion 





Several assumptions are made in obtaining 
equation 16: 

1. The rate of accumulation of sediments is 
constant. 

2. Sediments are homogeneous and have 
uniform mineral and chemical composition. 

3. Interstices are filled with liquid, and no 
gas phase is present. 



4. There is lateral homogeneity in the sys- 
tem, and a one-dimensional treatment is ade- 
quate. 

5. The effects of temperature and pressure 
are negligible. 

6. A steady state is attained ultimately. 

7. Chemical reactions obey first-order ki- 
netics. 

8. The diffusivity coefficient is constant. 

9. Interstitial water flow is laminar. 

10. Sediment grains and interstitial water 
are incompressible. 

11. After sufficient time, the sediment-water 
interface moves upward at a constant rate, and 
the depth profile of porosity remains station- 
ary with respect to the interface. 

12. The empirical porosity-depth relation- 
ship applies to clayey marine sediments. 

13. The sediment column can be approxi- 
mated by an infinitely thick column. 

Assumptions about the physical nature of the 
system are most nearly valid for sediments in 
an environment free of disruptive effects such 
as variable sediment supply and changes in 
thermal conditions. Assumptions about the 
kinetics of chemical reactions are valid for 
reactions involving substances that are present 
in excess. Although the reactions in the system 
modeled here are heterogeneous, empirical first- 
order kinetics are suggested by the apparent 
success of the model in the case of dissolved 
silicate considered later in this paper. The re- 
maining assumptions are necessary to provide 
a mathematically tractable model. 

A dimensionless form of (13) is 



aZ dr 

It is obtained by applying the transforms 



(17) 



r = k t T 


(18) 


Z ~ K Z 


(19) 


c- c ~ Cf 

Co Cf 


(20) 


The dimensionless constant, 









represents the ratio of advective effects to dif- 



508 



WILLIAM A. ANIKOUCHINE 




Fig. 2. Theoretical distribution of silicate in 
interstitial water fitted to data of Siever et al. 
[1965]. 



fusion and reaction. This ratio has a value of 
about 3 X 10" 5 in the case to be considered, 
which indicates that a simple diffusion-reaction 
model should suffice to describe the distribution 
of dissolved substances in interstitial water. 

Comparison of Theoretical Result 
and Empirical Data 

The validity of (16) can be examined by- 
comparing results based on (16) with empirical 
data from the literature. Measurements of sili- 
cate concentrations in interstitial water in sev- 
eral sediment cores were reported by Siever 
et al. [1965]. Two of these cores that exhibit 
uniform lithology and low degree of scatter of 
silicate concentrations were compared with the 
theoretically derived silicate concentration dis- 
tribution. The cores are L-139, a diatomaceous 
clay from the Gulf of California, and 258-5, a 
gray clay (upper part only) from the con- 
tinental shelf off Cape Cod, Massachusetts. 
The silicate concentrations in these two cores 
are fitted (Figure 2) by the curve 

c = 63 - 26 exp (1.9 X 10~ 2 z) (21) 

If we assume a diffusivity coefficient of 0.3 X 
10"* cm 3 sec" 1 , the reaction rate given by (16) 
is 10 X 10" 10 sec" 1 . This is smaller than the re- 
sults of Grill [1961] and Lewin [1961], who 
obtained constants of between 10" 7 and 10" 8 
sec" 1 in vitro silica dissolution experiments. It 
appears that the dissolution of silica in in- 
terstitial water is suppressed, perhaps by large 



concentrations of dissolved iron and aluminum 
[Lewin, 1961]. 

The model can be used in calculating the 
diffusive flux of a substance dissolved in in- 
terstitial water. The appropriate expression is 

-Z)|= -{k x DY% - C/ ) 

•expKV-D)" 2 ] (22) 
To illustrate the use of (22), we consider the 
distribution of dissolved manganese. If ex- 
tremely slow dissolution (k\ = 10" 12 sec" 1 ) is 
assumed to control the distribution of dissolved 
manganese, the diffusive flux of manganese at 
the sediment-water interface is 1.7 X 10"" g 
cm" 2 sec" 1 . This means that each year about 
0.5 gram of manganese is transferred from the 
sediments to each square meter of bottom. The 
values for c and c f used in this calculation, 
10"* g cm" 3 and 10" 3 g cm" 3 , are the concen- 
trations observed in seawater [Harvey, 1963] 
and in argillaceous rocks [Rankama and Sa- 
hama, 1950]. The diffusivity coefficient is as- 
sumed to be 0.3 x 10" 5 cm 2 sec" 1 . 

If the manganese in the interstitial water 
precipitates as nodules upon contact with the 
seawater and if it is assumed that the diameter 
of the nodules is 6 cm, their density is 2.8 
g/cm 3 , and the manganese content is 19%, 
about 14 x 10 3 years would be required for 
the accumulation of 120 nodules/m a . The 
growth rate of these nodules is about 2 mm/ 
1000 yr, a little larger than the rates (0.01 to 
1 mm/1000 yr) reported for rapidly growing, 
shallow-water nodules [Manheim, 1965]. These 
results suggest that, within the limitations of 
the model developed here, the source of man- 
ganese nodules is the interstitial water of the 
underlying sediments. 

Conclusions 

If compaction is included in a model of the 
interstitial water system, a simplification of 
the mathematics results even though advection 
caused by compaction is a negligibly small ef- 
fect. The diffusion-reaction, steady-state model 
yields distribution profiles that agree with 
empirical data on dissolved silicates and growth 
of manganese nodules. If assumptions made in 
developing the model are valid, empirical con- 
centration profiles can be examined for anoma- 






DISSOLVED CHEMICALS IN MARINE SEDIMENTS 



509 



lies. In this way the model can be used in 
interpreting the geochemistry of marine sedi- 
ments. 

Acknowledgments. I should like to thank Dr. 
M. G. Gross for his critical reading of the manu- 
script and for his helpful suggestions. 

References 

Athy, L. F., Density, porosity and compaction of 
sedimentary rocks, Bull. Am. Assoc. Petrol. 
Geologists, 14, 1-24, 1930. 

Berner, R. A., An idealized model of dissolved 
sulfate distribution in recent sediments, Geo- 
chim. Cosmochim. Acta, 28, 1497-1503, 1964. 

Berner, R. A., Chemical diagenesis of some mod- 
ern carbonate sediments, Am. J. Sci., 264, 1-36, 
1966. 

Goldberg, E. C, and M. Koide, Rates of sediment 
accumulation in the Indian Ocean, in Earth 
Science and Meteoritics, compiled by J. Geiss 
and E. D. Goldberg, pp. 98-100, North Holland 
Publishing Company, Amsterdam, 1963. 

Grill, E. V., A chemical study of nutrient regen- 
eration from phytoplankton decomposing in 
sea water, M.S. thesis, Department of Oceanog- 
raphy, University of Washington, Seattle, 1961. 



Harvey, H. W., The Chemistry and Fertility of 
Sea Waters, 2nd ed., pp. 146-147, Cambridge 
University Press, 1963. 

Koczy, F. F., Radioactive tracers in oceanogra- 
phy, Intern. Union Geodesy and Geophys. 
Monograph 20, 1961. 

Lewin, J. C, The dissolution of silica from diatom 
walls, Geochim. Cosmochim. Acta, 21, 182-198, 
1961. 

Long, D. V., Mechanics of consolidation with 
reference to experimentally sedimented clays, 
Ph.D. thesis, California Institute of Technology, 
Pasadena, 1961. 

Manheim, F. T., Manganese-iron accumulations 
in the shallow marine environment, Occasional 
Publ. 30, pp. 217-276, Narragansett Marine Lab- 
oratory, University of Rhode Island, 1965. 

Rankama, K., and Th. G. Sahama, Geochemis- 
try, p. 652, The University of Chicago Press, 
1950. 

Siever, R., K. C. Beck, and R. A. Berner, Com- 
position of interstitial waters of modern sedi- 
ments, J. Geol., 78, 39-73, 1965. 



(Received July 25, 1966.) 



Reprinted from MARINE GEOLOGY Vol. 5 
Marine Geology - Elsevier Publishing Company, Amsterdam - Printed in The Netherlands 



EVIDENCE FOR TURBIDITE ACCUMULATION IN TRENCHES IN THE 
INDO-PACIFIC REGION 1 

WILLIAM A. ANIKOUCHINE AND HSIN-YI LING 

Joint Oeeanographic Research Group, University of Washington, Seattle, Wash. (U.S.A.) 
Department of Oceanography, University of Washington, Seattle, Wash. (U.S.A.) 

(Received June 29, 1966) 



SUMMARY 

Sedimentary evidence in three cores taken from the Java, Mindanao and 
Mariana Trenches indicates that the Java and Mindanao Trenches are receiving 
sediments that are mostly turbidites. The Mariana Trench is receiving mostly pelagic 
muds with minor, but significant additions of sediments transported by turbidity flows. 



INTRODUCTION 

In 1964, cores (Fig.l) from the Java, Mindanao and Mariana Trenches, were 
taken from the ship U.S.C. and G.S. "pioneer" as part of the International Indian 
Ocean Expedition. The sediments in these eores exhibit unexpected textural and 
compositional features that indicate they are turbidites. 



METHODS 

The cores were taken with a large-diameter (3-inch) piston corer operated 
without a piston deactivator. The lower portions of the cores were disturbed, and 
were not analyzed. Analyses were performed by the senior author at the Pacific 
Oeeanographic Laboratory (POL), Institute for Oceanography, Environmental 
Science Services Administration, Seattle, Washington. The upper portions were 
logged (U. S. Department of Commerce, 1965), analyzed granulometrically, and 
examined under a stereomicroscope ( X 60). A summary of these data is presented 
in Fig.2, 3 and 4. The cores, both reference and working halves, are stored at POL. 



1 Contribution No. 2, Joint Oeeanographic Research Group and Contribution No. 389, Department 
of Oceanography, University of Washington, Seattle, Wash. (U.S.A.). 

Marine Geo!., 5 (1967) 141-154 



142 



W. A. ANIKOUCHINE AND H. Y. LING 




140° 



CHALLENGER 

SNELLIUS EXPEDITION CORES 

SWEDISH DEEP SEA 

EXPEDITION CORES 
PIONEER (USCaGS) 

TRENCH CORE POSITIONS 



^MINDANAO 
'/, TRENCH 

/264 
■ 108 

-271 



225 ,/M 

MARIANA - 
TRENCH 



<o '&*§ 



*^_ 




Fig.l. Location of cores taken in the Java, Mindanao and Mariana Trenches. 
Features diagnostic of turbidites 

Similarity between the sediment properties described on the following pages 
and the properties of turbidites listed by Kuenen (1964a) is presented as evidence 
of turbidites in the Indo-Pacific Trench cores. 

Maximum grain sizes 

The coarsest particles in the trench sediments fall within Kuenen's (1964) 
size limits. Grain sizes at the first percentile are coarser than very fine sand (4.5 phi) 
in Java and Mariana Trench sediments, and fine sand (3.5 phi) in Mindanao Trench 
sediments. 

Grading 

Pronounced grading occurs in the Java Trench core. A bed grades 2.3 phi 
units over 10 cm in one case. Less well-defined graded beds occur throughout the 
core. Size grading was not observed in the sediments in the Mindanao Trench core; 
however, the contacts between beds of coarse and of fine texture are often transitional 
over several centimeters. This grading of texture can be considered as graded bedding 
in this core. In the Mariana Trench core, the size and abundance of mud lumps grades 
uniformly in beds up to 20 cm thick. There is no corresponding gradation in mean 
grain size in these sediments. 



Marine Geo!., 5 (1967) 141-154 



INDO-PAOTIC TURBIDITES 



143 




/<?/&/ 
&&%&' 



A// 



'$/s3 



WiS£. 



ffr/x. 



W*M&ffito&,. 



#1 



<9 



w4m/£MmMZmw/f 










20 




40 




60 




80 


E 
o 


100 


2 


120 


I 

Q. 
UJ 
Q 


140 
160 




180 




200 




220 




240 




260 



5Y6/I 



5GY6/I 



> - , 



2 — 



29 — 



59 _ 
63 — 
69 — 
83 — 

91 — 

119 — 



151 — 



178 — 



210 — 



249 — 



7.58 



8.05 



7.72 
6.61 
5.35 
4.69 
7.48 

7.43 



7.84 



7.89 



623 



7.64 



□ 



LUTITE 

SILT 

HEAVY FRACTION 

LIGHT FRACTION 

TOTAL FRACTION 

PRESENT 

ABUNDANT 

FLOOD 

TRACE 





|2T 
3H 
/3L 
4T 






t 






X 




























X 










A 
























28.5 




? 


A 


X 
































F 


F 














t 










t 












i2T 
/3T 

I/4T 






A 




































X 








t 
























36.2 










F 
































///3H 

//3L 

f//4T 


t 










t 




























X 


































30.0 




X 


t 






t 






























///3H 
//3L 
I/4H 
i 4L 






















X 
















2.16 'I 


X 












X 






















I7.0 




A 








t 


























2.04 '] 


A 








A 




X 
























/3H 
/3L 
' 4T 


X 






































X 


t 










t 






















8.2 


2.27 % 


F 


t 






t 




























1.63 ' 

1.04*; 


/3H 
' 3L 
\4T 


F 




































F 


t 
































2.6 


0.57 C 


F 


t 






X 






























3H 
\ 3L 


X 










t 


























2.23 k 




X 


X 


A 


1 
















t 










32.3 




X 


X 


X 


X 


A 




\ 
















t 


t 


t 






I 2T 
\ 3H 
\3L 
\\4T 




X 


X 






X 




























X 






t 




A 
























28.6 


2.41 k, 




X 


X 


A 


t 




























A 


A 


X 


A 


X 






























3H 

\ 3L 
\\4H 

\\4L 


X 




































2.08v 


X 


A 


t 








t 










X 




t 








39.0 




X 






X 






X 
























X 


A 


t 


A 






A 
























l.70v 


\3H 
\\3L 
















A 




X 








X 


X 


t 


t 








X 






X 




X 






















35.5 




X 


t 


t 


F 


X 
















t 


t 










2.21 . 


\3H 
,\3L 
\*T 


X 




































X 


t 






t 


























I4.9 




A 


t 






X 






























\ 3H 
\ 3L 
\4T 


X 






































X 


A 
































30.0 




A 


A 



































Fig.2. Java Trench core (PI-442-64-33) sediment analysis data. Numerical values in mean grain size, 
sorting and size fraction columns are in phi units. 



Marine Geol, 5 (1967) 141-154 



144 



W. A. ANIKOUCHINE AND H. Y. LING 







/3H 






























X 








3L 




X 
















t 








A 








35.8 


\ 4H 






























X 






\4L 












X 








X 








A 




t 






^3H 










X 
























X 




3L 


X 
























X 








1 1.9 


\ 4H 










X 


X 










X 






A 




X 




\4L 








t 












A 








A 










^2T 




F 


X 
































v 3T 


A 


X 


X 






























26.4 


\4T 


A 

A 










t 
















t 




t 






/2T 


X 


t 


X 






























/3T 


A 

A 


X 


t 


X 




























35.0 


/ 4T 


X 


t 


/ 






























2T 




































7.4 


\4T 




X 








A 


A 








t 


X 




A 








/IT 




F 


X 
































' 2T 




A 


F 






























30.1 


\ 3T 


iA_ 


A 
































\4T 


A 










t 










t 
















/2T 


A 


X 


































\ 3T 


A 


F 


t 






























46.7 


\4T 


A 


X 


X 


X 






























/it 






































/2T 


A 


X 


t 


X 




























40.1 


/ 3T 


^A 


X 


t 


X 




























4T 


A 


X 


X 


X 






























'/3H 










X 
























1 




/ 3L 


t 


F 




X 




t 
















t 








35.6 


4H 










t 














X 


X 


X 








^4L 




X 
























A 










/IT 


X 


F 


X 
































<* 2T 




F 


A 






























47.4 


> 3T 


X 


F 


X 


X 




























\4T 


X 


F 


X 


X 




















t 










I-2T 














X 
























OT 






X 








X 
























IT 




t 


A 








X 






















33.8 


2T 






A 








X 






















\ 3T 


X 


X 


A 








t 
























"--\41 


F 


F 


































\ IT 


A 




X 
































\\ 2T 


A 




t 








t 


X 




















35.8 


\\ 3T 


A 


X 


X 


t 






X 


X 






t 














\\4T 


A 


X 


X 


X 






X 


X 


X 




X 






t 










\ 3T 




F 




X 




















X 








41.5 


\4T 




F 




X 




X 








X 


X 






X 









I I LUTITE 
IH^ MUD LUMPS 
EE3 SILT 

E551 DIATOM OOZE 
P77I WOOD 

H HEAVY FRACTION 

L LIGHT FRACTION 

T TOTAL FRACTION 

X PRESENT 

A ABUNDANT 

F FLOOD 

t TRACE 

Fig.3. Mindanao Trench core (PI-442-64-35) sediment analysis data. Numerical values in mean size, 
sorting ana size fraction columns are in phi units. 



Marine Geol., 5 (1967) 141-154 



INDO-PACIFIC TURBIDITES 



145 





20 

S 40 

? 60 

I 80 
o_ 

LU 100 
Q 

120- 

140 



I0YR6/2 
I0YR4/2 



I0YR5/2 



I0YR4/2 



7YR4/2 



5YR5/4 




13 — 
30 — 



60- 



105 ■ 



139 — 



5.53 
4.04 

7.74 



5.99 



6 55 
6.01 
6.10 

4.10 



2.95' 



4.10, 



□ 


LUTITE 


m 


MUD LUMPS 


m 


SILT 


H 


HEAVY FRACTION 


L 


LIGHT FRACTION 


T 


TOTAL FRACTION 


X 


PRESENT 


A 


ABUNDANT 


F 


FLOOD 


t 


TRACE 



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A 
















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t 














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A 








t 






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X 


















X 


















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t 


X 








X 




t 


X 




t 


t 


t 




t 








3L 


X 


X 


t 


A 




X 


t 












X 




t 






t 


t 




19.4 


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X 


X 








t 




X 


X 


A 


X 


X 


















/3H 












X 






X 


X 






t 


















; 3L 








t 




A 


t 












A 




t 












30.7 


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X 










A 






X 


A 
















X 






41 




1 








t 




t 










A 








X 


X 




X 




,'2T 




t 








X 






t 








X 




X 














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X 






X 


X 
















X 






22.7 


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J^ 


X 


X 






X 






X 


X 


t 




A 




X 




X 


t 






4T 


X 








X 


X 




X 


X 


X 


t 


F 








t 


t 








Ah 










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X 














t 








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X 


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X 


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37.7 


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X 


X 


A 




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X 












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X 


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X 


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t 


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t 








X 














X 


29.2 


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t 










A 








A 
















t 






\4I 


X 


X 


X 


t 




X 














X 


















3H 










F 


A 








t 
























3L 


t 


A 




X 




A 




t 










X 
















35.1 


L4H 


1 










X 






X 


X 




X 








A 




t 






\4L 


X 


X 


X 


t 




X 














X 


















3H 










X 


A 








X 




t 




















3L 








t 




A 














X 
















19.1 


i4H 












F 






X 


A 




A 








X 










4L 




A 


A 






A 






t 


X 






A 



















Fig.4. Mariana Trench core (PI-442-64-36) sediment analysis data. Numerical values in mean grain 
size, sorting and size fraction columns are in phi units. 



Sorting 

The generally poor sorting in these cores does not agree with the moderate to 
good sorting cited by Kuenen (1964a, p. 10) as typifying deep-sea sands. The disparity 
probably is caused by excessive amounts of lutite in the trench core sediments. 

Inorganic constituents 

Beside clay minerals, the most abundant component, trench sediments contain 
angular quartz, mica, feldspar and pyrite. These are all cited (Kuenen, 1964) as 
existing in turbidites. These materials are not diagnostic of their depth of original 



Marine Geol , 5 (1967) 141-154 



146 W. A. ANIKOUCHINE AND H. Y. LING 

deposition but the presence of rock fragments and feldspar suggests that the materials 
have undergone few sedimentary cycles. 

Origin and distribution of organic constituents 

Organic materials in the trench sediments are mostly the remains of siliceous 
planktonic organisms. Foraminifera in the Java Trench core occur principally in 
fine-textured layers. In the Mindanao Trench core, the diatom, Ethmodiscus rex 
(Plate IB, C), occurs only in certain coarse-textured layers (Plate 1A). All other 
organic remains (Radiolaria, sponge spicules, .fish teeth and wood occur in both 
fine and coarse-textured layers. Fish teeth and fish bone fragments occur throughout 
the Mariana Trench core, but most of the Radiolaria occur in layers containing 
abundant mud lumps. 

Of all organic constituents in these sediments, the wood is unquestionably 
of terrestrial origin. Fish bones and sponge spicules might be of neritic origin. It 
is difficult to interpret the origin of the few tubular, arenaceous Foraminifera found 
in Java Trench core or of the other organic constituents in the Mindanao and Mariana 
Trench cores. 

Lamination 

The sediments from the Java Trench and Mindanao Trench cores are strongly 
and irregularly laminated. Laminae range in thickness from a few millimeters to as 
much as 20 cm. Alterations in sediment laminae are marked by changes in color and 
texture or, in silt streaks, by changes in mean grain size. 

Layering in the Mariana Trench core is marked by changes in texture and by 
subtle changes in color. Textural changes reflect changes in the amounts of mud 
lumps present in the laminae. The thickness of lamina of lutite is similar to the other 
trench cores. Silt occurs in streaks about 1 mm thick or layers as much as 20 cm thick. 

Distorted beds 

These are found in the sediments from the Java Trench and Mariana Trench 
cores. Sediments with contorted bedding lie between layers having normal bedding 
in the Java Trench core. In the Mariana Trench core there are irregular silty lenses 
lying about 50° to the core axis. These lenses lie between layers having bedding normal 
to the core axis. 

Ripple lamination 

A structure resembling cross-bedding occurs in the core from the Java Trench. 
Streaks of fine sand, 1-2 cm apart, accentuate bedding surfaces tangential to the 
underlying layer and truncated by the overlying layer. This structure is about 5 cm 
thick and may be a portion of a large-scale ripple mark. No ripple marks were found 
in the other two trench cores. 

Marine Geol., 5 (1967) 141-154 



PLATE I 



H* 



A 



3*?$t?52E 






' 



icSt. t ? 



'•■tf-^w 




B 



5wSSSBt'j*sC?^fiS8»S!a<<vi'"- 




Photograph of a portion of Mindanao Trench sediment core (PI-442-64-35) showing the alter- 
nation of lithology. Occurrence of diatom, Ethmodiscus rex, in seidment with coarse texture is 
indicated by white arrow. Mud lump layers occur at 56 cm and at 87 cm. 

Photomicrographs of central area of Ethmodiscus rex from Mindanao Trench core sample, 
137-138 cm below sediment surface; x 250 (phase contrast). 

Photomicrographs of central area of Ethmodiscus rex from Mindanao Trench core sample, 
137-138 cm below sediment surface; x 770 (phase contrast). 



148 W. A. ANIKOUCHINE AND H. Y. LING 

Mud lumps 

Mud lumps occur in all three cores. They are about 1 mm in diameter in the 
Mariana Trench core and about 1 cm in diameter in the Mindanao Trench core 
(Plate IA). Only a few large (up to 3 cm in diameter) lumps occur in the Java Trench 
core. The lumps have the same color as the surrounding sediment. 

An analysis of mud lumps indicated that they are not aggregations of the sur- 
rounding fine-textured sediment. Sand-silt-clay ratios for disaggregated mud lumps 
are plotted onFig.5, 6 and 7 as open circles. Ratios for the sediments including mud 
lumps are plotted as solid circles. 

The sediments from the Mindanao Trench core have sand-silt-clay ratios 
that fall along the dashed line in Fig.6. Because mud lumps fall in the sand size, 
their removal from the sediment should not affect the silt-clay ratio of the remaining 
material and the ratio should remain that indicated by the dashed line in Fig.6. 
Ratios for disaggregated mud lumps do not fall near the dashed line, indicating a 
silt-clay ratio different from that of the complete sediment. 

In the sediments from the Mariana Trench core (Fig. 7), there is no linear trend 
in sand-silt-clay ratios. However, a line drawn through the sand apex and a solid 
circle intersects the silt-clay axis at a point representing a silt-clay ratio lower than 
that of the mud lumps removed from that sediment. It appears that these mud lumps 
are not formed in situ. 



CLAY 




SAND^ *SILT 

Fig.5. Java Trench core triangular diagram of size components. 

Marine Geol., 5 (1967) 141-154 



INDO-PACIFIC TURBIDITES 



149 



CLAY 



SAND 




SILT 



Fig.6. Mindanao Trench core triangular diagram of size components. 



CLAY 



SAND 




SILT 



Fig.7. Mariana Trench core triangular diagram of size components. 



Marine Geol., 5 (1967) 141-154 



150 W. A. AN1KOUCH1NE AND H. Y. LING 

Thickness 

The thickness of sediment layers interpreted as turbidites varies from a few 
millimeters to about 18 cm. If the entire series of alternating layers in the cores from 
the Java and Mindanao Trenches represents deposition from a single turbidity flow, 
then the thickness of the deposits exceeds the lengths of these cores; i.e., 2.5 and 4 m, 
respectively. In the Mariana Trench core, turbidites are a graded mud lump layer 17 
cm thick and possibly streaks of silt less than a millimeter thick. 

Contacts 

In the Java Trench core most contacts are sharp. In only two cases gradational 
upper boundaries were observed. The Mindanao Trench core shows sharp contacts 
with several gradational upper contacts and a few gradational lower contacts. Both 
contacts are gradational in a few layers. Few distinct contacts appear in the Mariana 
Trench core; these are sharp rather than gradational. 

Burrowing 

Evidence of burrowing is restricted to the upper few centimeters of the Java 
and Mindanao Trench cores and the upper 70 cm of the Mariana Trench core. The 
Java Trench core shows thin zones of oxidized coloration at 40, 70 and 88 cm. These 
zones of oxidized sediments represent either pelagic sediments deposited at the top 
of turbidite accumulations or the oxidized upper portions of individual turbidite 
layers. 

Erosion at lower contacts 

Many of the thin layers of sediment in the Java Trench core have thin streaks 
of coarse mica at their lower contact. In the Mindanao Trench core a few layers 
have a unit thickness of mud lumps, diatom frustules, or silt streaks at their lower con- 
tact. No such feature occurs in the Mariana Trench core. Kuenen (1964b) interprets 
this feature as a lag deposit resulting from erosion of the underlying layer. Although 
he refers to erosion of a pelagic layer, one could expect erosion of an underlying 
turbidite layer if turbidity flows occurred in rapid succession. The only condition is 
that the underlying layer be uncompacted. 

Alternations of layers 

There is a contrast in the amount of microorganisms in the layers in the Java 
Trench core. Layers of fine-textured sediments contain Foraminifera and Radiolaria, 
whereas coarse-silt layers with coarse texture and containing considerably more mica 
contain only a trace of these organisms. 

Marine Geol., 5 (1967) 141-154 



INDO-PACIFIC TURBIDITES 1 5 1 

The Mindanao Trench core has alternating layering that shows a contrast 
among three sediment types. Fine-textured sediment layers are rich in Radiolaria, 
the diatom Ethmodiscus rex, and organisms tentatively identified as Foraminifera. 
Layers rich in clay lumps are free of diatoms and contain only a few Radiolaria. 
Ethmodiscus ooze layers contain a rich microfauna. These ooze layers contain a 
large amount of Frustules, have a coarse texture, and lack the rock fragments and 
mineral grains present in fine-textured layers. The sediments in the Mariana Trench 
core are mainly uniform and finely textured with interbedded, graded layers of mud 
lumps and streaks and lenses of silt. 

Color bands and variegation up to 1 cm thick in the Java and Mindanao Trench 
cores present striking evidence that a nonuniform environment of deposition exists 
in these trenches. 

Influence of source materials 

This influence is striking if the three trench cores are compared. The Java 
Trench receives sediments rich in mica. The Mindanao Trench receives sediments 
either rich in clay lumps, silt and terrestrial plant debris, or rich in Ethmodiscus rex. 
Besides pelagic brown mud, the Mariana Trench receives silt and mud lumps. The 
existence of two ore more sediments in two of these cores indicates that more than 
one source may supply a single trench even though the diversity of materials may be 
transported to the site of deposition by a single mechanism; e.g., a turbidity flow. 

Influence of distance to source 

Of the three trenches studied, the Mariana Trench is the farthest from a major 
land mass. This is reflected by the preponderance of pelagic sediments and the thin- 
ness of the silt layers in the Mariana Trench core. The coarseness of the mud lumps 
and thickness of the graded mud lump layer in this core suggest that the source of 
the mud lumps is much closer. 

The Mindanao and Java Trenches lie close to major land masses. In the Java 
Trench core, the layers of coarse mica are thicker (up to 10 cm) and closer together. 
The interbedded lutite comprises about 80% of the core. The Mindanao Trench 
core contains still less fine-textured lutite. The Java and Mindanao Trenches lie about 
the same distance from nearest major land masses, therefore other factors such as 
frequency or degree of tectonic activity (Bezrukov and Petelin, 1959) and amount 
of relief and type of drainage of the land masses must exert influences upon the 
nature of turbidite accumulation that override the influence of distance to source. 

Pelagic interbeds 

The pelagic sediments in the Mariana Trench core are brown mud (clay) 
typical of open ocean abyssal regions. The only organic materials found in this 

Marine Geo/., 5 (1967) 141-154 



152 W. A. ANIKOUCHINE AND H. Y. LING 

sediment are fish teeth and bones, and possible faecal pellets. The pelagic sediments 
in the Java Trench core are fine-grained, micaceous, gray-green lutites. The Mindanao 
Trench core appears to contain few pelagic interbeds. These are fine-grained lutites 
containing Radiolaria but few or no diatoms. 

Slope of bottom 

Slopes were not measured in the areas of the three trench cores. It is likely 
that the slope of some of the bottom of the trenches is less than a degree so that 
turbidites can accumulate there. 



DISCUSSION 

The sediments in all three trench cores contain several features typifying tur- 
bidites. Although it is not reasonable to identify the sediments in Mariana Trench 
core as turbidites, the effects of turbidity flows can be recognized in these sediments. 
The abundance of evidence leaves little doubt that the sediments in the Java and 
Mindanao Trench cores are turbidite accumulations. 

The sediments in the Java Trench core are interpreted as hemipelagic micaceous 
lutites alternating with graded and ungraded micaceous silts that are introduced by 
turbidity flows. There is only a single source of sediments, presumably the island of 
Sumatra. Of the three cores studied, the Java Trench core presents the least complex 
example of turbidite accumulation. 

The turbidite accumulations in the Mindanao Trench core are the most com- 
plex. The sediments in this core are interpreted to be a turbidite sequence of lutites 
containing Radiolaria and diatoms interbedded with terrigenous silts, mud lump 
accumulations and Ethmodiscus ooze. It is possible that the lutite layers are hemipe- 
lagic. However, the occurrence of wood fragments in these layers argues against this 
interpretation. It is more likely that lutite is introduced to the core site by turbidity 
flows originating close to the coast of Mindanao Island. Mud lumps probably result 
from mass movement of preexisting sediments from higher portions of the trench. 
Bezrukov (1957) reached the same conclusion regarding the Izdu-Bonin and Mariana 
Trenches. 

Several observations indicate that Ethmodiscus frustule fragments are trans- 
ported to the core site, presumably by turbidity flows. Although the three trenches 
are located within the biogeographic distribution region of Ethmodiscus rex (Semina, 
1959), the occurrence of Ethmodiscus ooze in these cores and in others from the Indo- 
Pacific region (Neeb, 1943; Olausson, 1960; Zhuze et al., 1959) is erratic. The ooze 
occurs in the Mindanao Trench core in irregularly spaced layers between 75 and 328 
cm. It is rare in the Java Trench core and is absent from the Mariana Trench core. 
Neeb (1943) reports no significant amounts of diatoms in cores from the Mindanao 
Trench taken during the "Snellius" Expedition (Fig.l), but Kolbe (1954) states that 

Marine Geol., 5 (1967) 141-154 



INDO-PACIFIC TURBIDITES 153 

diatom fragments thought to be Ethmodiscus rex are found in "nearly all cores and 
levels of the Equatorial Pacific." 

Semina (1959) found no close relationship between the presence of Ethmodiscus 
rex in sediments and in the water above. She is inclined to agree with Kolbe (1957), 
Hendey (1958) and Zhuze et al. (1959) that there are other factors, e.g., bottom 
current, flow of the ooze, or irregular submarine topography, that control the distri- 
bution of this diatom ooze on the present-day ocean bottom. Riedel (1954) reexa- 
mined the Radiolaria assemblage from the original "Challenger" Station 225 
(11°24.0'N— 143°16.0'E; depth: 4,475 m) and concluded that "There is little doubt 
that the sediment obtained at "Challenger" Station 225 is an outcrop of Middle 
Tertiary Radiolarian ooze. The occurrence of Ethmodiscus rex in this sediment has 
no connection with its existence in the overlying water at the present day, but rather 
means that the diatom lived in that region during Middle Tertiary time." These 
observations are in accord with the concept that Ethmodiscus ooze accumulates 
within the limits of its biogeographical region but is transported by occasional 
turbidity flows, so that its distribution on the bottom is patchy and its distribution 
within bottom sediments is irregular. 

The sediments in the Mariana Trench core contain fewer features typical of 
turbidites than do the sediments in the Java and Mindanao Trench cores. Neverthe- 
less, the features found in the Mariana Trench core, e.g., graded mud lump layers 
and silt streaks, are just as important because they show that nonpelagic sediments 
with properties characteristic of turbidites can occur in a trench remote from land 
and separated from land by several ridges and basins. 

It is likely that mud lumps are introduced into the Mariana Trench by mass 
movement such as sliding or slumping; the dislocation of slightly compacted clay is 
probably the mechanism whereby the mud lumps are formed. The silt in layers and 
streaks has been transported from distant terrestrial sources. The mechanisms for 
the transportation of this material cannot be specified at present. 



acknowledgements 

The authors wish to thank D. A. McManus for reading the manuscript. The 
work of the junior author was supported by the Office of Naval Research Contract 
No.477(37), Project NR 083-012. 



REFERENCES 

Bezrukov, P. L., 1957. The sediments of the Izdu-Bonin, Marianas and Ryudu deep-sea oceanic 

depressions. DokL: Earth Sci. Sect. (English TransL), 114 : 393-396. 
Bezrukov, P. L. and Petelin, B. P., 1959. The bottom sediments of the trenches of the western 

Pacific Ocean. Intern. Oceanog. Congr., 1, Preprints Abstr. Papers, pp.451-452. 
Hendey, N. I., 1958. Diatoms from equatorial Indian Ocean cores. Nature, 181 (4614) : 953-954. 

Marine Geol., 5 (1967) 141-154 






154 W. A. ANIKOUCHINE AND H. Y. LING 

Kolbe, R. W., 1954. Diatoms from equatorial Pacific cores. Rept. Swed. Deep-Sea Expedition, 

1947-1948,6(1): 1-49. 
Kolbe, R. W., 1957. Diatoms from equatorial Indian Ocean cores. Rept. Swed. Deep-Sea Expedition, 

1947-1948, 9 (1) : 1-50. 
Kuenen, Ph. H., 1950. Marine Geology. Wiley, New York, N.Y., 568 pp. 
Kuenen, Ph. H., 1964a. Deep-sea sands and ancient turbidites. In: A. H. Bouma and A. Brouwer 

(Editors), Turbidites. 3. Developments in Sedimentology. Elsevier, Amsterdam, pp. 1-33. 
Kuenen, Ph. H., 1964b. The shell pavement below oceanic turbidites. Marine Geol., 2 : 236-246. 
Neeb, G. A., 1943. The composition and distribution of the samples. Snellius Expedition, Sci. Results 

Snellius Expedition Eastern Pt. East-Indian Geol. Archipelago, 1929-1930. 5. Results. 3. Bottom 

Samples, 268 pp. 
Olausson, E., 1960. Description of sediment cores from the central and the western Pacific with the 

adjacent Indonesian region. Rept. Swed. Deep-Sea Expedition, 1947-1948, 6 (5/8) : 161-214. 
Riedel, W. R., 1954. The age of the sediment collected at "Challenger" (1875) Station 225 and the 

distribution of Ethmodiscus rex (Rattray). Deep-Sea Res., 1 (3) : 170-175. 
Semtna, G. I., 1959. The distribution of the diatom Ethmodiscus rex (Wallich) Hendey among the 

plankton. Dokl: Earth Sci. Sect. (English Transl.), 124 (6) : 1309-1312. 
U. S. Department of Commerce, 1965. International Indian Ocean Expedition, U.S.C. and G.S.-Ship 

Pioneer — 1964. 1. Cruise Narrative and Scientific Results. U. S. Govt. Printing Office, Washing- 
ton, D. C, 139 pp. 
Zhuze, A. P., Petelin, V. P. and Udintsev, G. B., 1959. Concerning the origin of diatomaceous 

muds containing Ethmodiscus rex (Wallich) Hendey. Dokl. Earth Sci. Sect. (English 

Transl). 124(6) : 1301-1304. 



Marine Geol, 5 (1957) 141-154 



10 



Reprinted from JOURNAL OF GEOPHYSICAL RESEARCH 
Vol. ?2, No. If The American Geophysical Society 



Journal of Geophysical Research 



Vol. 72, No. 24 



December 15, 1967 



Heat Flow in the Pacific Ocean off Central California 

Robert E. Burns and Paul J. Grim 
Institute jor Oceanography, ESSA, Seattle, Washington 9S102 

As part of the Upper Mantle Project, a marine geophysical survey has been conducted off 
central California, between 35° and 39°N, extending about 800 km offshore. Heat flow measure- 
ments were made at thirty-one stations including twelve along a special section between the 
highest and the lowest values previously reported. The heat flow is relatively constant (1.7 to 
1.8 Meal cm" 2 sec" 1 ) over the eastern part of the continental rise; farther offshore a banding of 
high and low heat flow on a regional scale (wavelengths of several hundred kilometers) is 
present. Shorter wavelength fluctuations (about 50 km) in the heat flow are detected by the 
closely spaced stations along the special section. 



Introduction 

As a part of the Upper Mantle Project 
(UMP), the seaward extension of the transcon- 
tinental geophysical survey in the Pacific has 
been surveyed by the U.S. Coast and Geodetic 
Survey. An initial set of measurements was 
made from the Pioneer in 1965, and the Sur- 
veyor completed the work in the spring of 1966. 
Data were collected in an area located between 
35° and 39°N extending about 800 km offshore 
into the Pacific. The basic series of measure- 
ments included measurements of bathymetry, 
gravity, total magnetic intensity, and sea floor 
heat flow. This report is principally concerned 
with the heat flow measurements, but it includes 
tentative interpretations as to their implications 
in view of the other geophysical parameters. 

The area covered by the investigation (Fig- 
ure 1) includes several important physiographic 
units [Menard, 1964] including the continental 
shelf, slope, and the two large sedimentary fans 
(Delgada and Monterey) that encroach on the 
area of abyssal hills to the west. Also within 
the area is the eastern part of the Pioneer ridge, 
extending westward from the Delgada fan be- 
tween 38° and 39°N. Although there has been 
some geophysical work done in this area in the 
past, it has not been as comprehensive as the 
work on the East Pacific rise to the southeast 
or the work done in the general area of the 
Mendocino fracture zone immediately to the 
north. 

The program of heat flow measurements 
was motivated by several considerations. Von 
Herzen [1964] reported a banding of high, 



normal, and low heat flow trending generally 
north-south in the region north of the Mendo- 
cino fracture zone and suggested that the trends 
might cross to the south without being offset. 
From the area to the south, a banding of high 
heat flow had been reported along the East 
Pacific rise [Von Herzen and Uyeda, 1963; 
Langseth et al., 1965], and several scattered 
measurements (Figure 1) of heat flow have been 
reported from within the study area [Foster, 
1962; Von Herzen, 1964]. Of particular interest 
before the UMP work was the apparent con- 
trast between the relatively consistent values 
associated with the eastern part of the con- 
tinental rise and the presence of scattered high 
and low values over most of the offshore area. 
In this study, specific interest was directed to 
the high (3.45 ^cal cm" 2 sec" 1 ) reported by Von 
Herzen [1964] at 38°25'N, 126°09 / W and the 
low (0.6 /xcal cm" 2 sec" 1 ) reported by Foster 
[1962] at 38°35'N, 127°45'W. In view of these 
data and the constraints of available ship time, 
the basic objectives of the heat flow phase of 
the UMP investigation were (1) examination 
of the eastern part of the continental rise to 
ascertain if it has the relatively uniform heat 
flow that the earlier data implied, (2) verifica- 
tion of the high and low values reported by 
Von Herzen and Foster, and (3) examination of 
the area between these stations to determine the 
spatial extent of the high and low values (if 
they were verified). 

Method and Results 

The instrumentation used for the heat flow 
measurements was basically the Ewing thermo- 



6239 



G240 



BURNS AND GRIM 




(i) 



• SURVEYOR -CONFIDENCE HIGH 
o 5<y/?l//f>W-C0NFIDENCE "LOW 
▲ WW£"£7?-C0NFIDENCE "HIGH" 
A ^/O/Vff/P-CONFIDENCE "LOW" 
D PREVIOUS REPORTS 

(VH)-VON HER2EN. 1964 

(F)-FOSTER, 1962 





Fig. 1. (Top) Map of Upper Mantle Project area off California. Fourteen heat flow stations, 
shown below, lie along A-A'. Bathymetry and the total magnetic field were obtained along 
A-A' , B-B', C-C, and D-D'. The hatched areas represent areas having relief of over 100 
meters. Physiographic provinces are based on the map of Menard [1964]. (Bottom) Heat 
flow values to the nearest tenth in cal cm" 2 sec" 1 X 10" 6 . Previously published values by 
Foster [1962] and Von Herzen [1964] are indicated by F and VH. Pioneer stations are shown 
by triangles; Surveyor stations, by circles. Solid circles or triangles indicate high-confidence 
values and open circles or triangles indicate low-confidence values, as explained in the text. 
(The remaining figures in this paper, which show heat flow, use this method of identification.) 
Station numbers from Pioneer and Surveyor are in parentheses and correspond to numbers in 
Table 1. Contours, in meters, are from the map by Menard [1964]. 



grad [Gerard et al., 1962; Langseth, 1965]. The 
equipment and the many uncertainties inherent 
in the general method of estimating heat flow 
have been discussed at length by many previous 
investigators (see for example, Lachenbruch 
and Marshall [1966] and Langseth [1965]), and 
these aspects will not be discussed in this paper. 
The thermal conductivities were determined 



from thermal resistivity estimates based on 
water content of the sediments collected by the 
coring device, using the linear relationship re- 
ported by Bullard and Day [1961]. The results 
of the measurements are tabulated in Table 1. 
The values of heat flow reported in Table 1 
are simply the products of the conductivity and 
the gradient. The indicated confidence has been 



HEAT FLOW IN PACIFIC OCEAN 



6241 



estimated by alternative methods, depending on 
how many thermistors actually penetrated the 
bottom. 

When three thermistor probes were in the 
sediment, independent estimates of heat flow 
were made over the two intervals between the 
thermistors. Using the notation of Lachenbruch 
and Marshall [1966], where (q) is the average 
and Aq is the difference of the two heat flow 
values, 'high' confidence is indicated for values 
of Aq/2(q) less than 10% and 'low' confidence 
is indicated for values greater than 10%. 

When only two probes were in the sediment, 
the estimate of confidence is based on the un- 
certainty in the determination of both the 
thermal gradient and the thermal conductivity. 
When temperature differences between the 
two probes were read from several places on the 
record and were equal or differed by less than 
0.01 °C, the temperature gradient was consid- 



ered high confidence; a greater range was con- 
sidered low. For conductivity, where AK is the 
range of values and (K) the average, values of 
AK/2(K) of less than 10% were considered 
high confidence; a value greater than 10% (or 
if there was only one determination of K) was 
considered low. The confidence estimate in 
Table 1, for the stations in which only two 
probes penetrated the sediment, is reported high 
only if both the temperature gradient and the 
thermal conductivity were accepted with high 
confidence. 

In the cases (stations P-10, P-15, P-22) where 
no sediment sample was obtained, the reported 
(K) is the regional mean, and the listed heat 
flow is considered a low confidence estimate. 

If the eight measurements of heat flow pre- 
viously reported from the area (see Figure 1) 
are included, a total of thirty-nine heat flow 
measurements are now available from the UMP 



TABLE 1. Heat Flow Measurements Taken during Upper Mantle Project Marine Geophysical Survey 



Station* 



North 
Latitude 



West 
Longitude 



Depth, m 



No. Conductivity 

Probes Conductivity X 10' cal/cm 
in Mud Samples sec °C 



Heat Flow 
Gradient X 10«, 

X 10 8 , °C/cm cal/cm J sec 



Confidence 



S-l 


39°01.6' 


129 "59 .7' 


4456 


3 


S-2 


35°29 0' 


132 "00. 4' 


5167 


3 


S-3 


35 "29. 5' 


130 "58. 6' 


5090 


3 


S-4 


35 "29. 7' 


130 °01 7' 


4858 


3 


S-5 


35°29.2' 


128°59.0' 


4796 


2 


s-e 


37°28 2' 


123°50.5' 


3514 


3 


S-7 


37°59.7' 


124°53.2' 


3959 


3 


S-8 


38 "10. 2' 


125°28.0' 


3937 


3 


S-9 


38°24.1' 


126 "02. 2' 


4264 


3 


S-10 


38°29.3' 


126°43.0' 


4467 


2 


S-12 


38 "35 3' 


127 "30. 9' 


4613 


2 


S-14 


38°45.1' 


128°59.0' 


4533 


2 


S-16 


38 "31. 4' 


127°08.3' 


4551 


3 


S-19 


38°29.1' 


126 "43.0' 


4494 


2 


S-20 


38 "27. 4' 


126 "28. 9' 


4403 


3 


S-21 


35 "48. 3' 


122 "59. 7' 


3710 


3 


S-22 


36°59.9' 


123 "38. 0' 


3425 


3 


S-23 


36 "59. 5' 


124°22.4' 


4052 


2 


S-24 


36°49.7' 


124 "45. 9' 


4290 


2 


S-25 


36 "39.0' 


125 "10. 5' 


4194 


2 


P-3 


36 "56. 9' 


127 "55. 3' 


4635 


4 


P-10 


38°35.1' 


127 "15. 9' 


4462 


3 


P-12 


38 "19 1' 


124 "01 .8' 


3273 


2 


P-13 


38 "30.1' 


124 "15. 3' 


3438 


3 


P-15 


37 "55. 5' 


123 "49. 9' 


3310 


3 


P-16 


37 "47. 5' 


124 "16. 9' 


3465 


3 


P-17 


38°25 2' 


126 "08. 2' 


4370 


3 


P-18 


38°25.6' 


126 "19 .8' 


4224 


3 


P-20 


38°29.3' 


126 "47. 6' 


4370 


2 


P-21 


38°31.9' 


127 "03. 6' 


4416 


2 


P-22 


38 "34. 3' 


127 "12 7' 


4452 


3 



1.94 


0.30 


0.58 


High 


1.95 


0.98 


1.91 


High 


1.91 


2.40 


4.58 


High 


1.86 


0.84 


1.56 


High 


1.82 


1.18 


2.14 


High 


2.00 


0.98 


1.96 


High 


1.95 


0.86 


1.68 


High 


1.83 


0.97 


1.77 


High 


1.88 


0.97 


1.82 


High 


1.95 


0.73 


1.42 


High 


2.00 


0.15 


30 


High 


1.88 


0.25 


0.47 


Low 


1.99 


0.64 


1.27 


Low 


1.98 


0.72 


1.42 


Low 


1.93 


0.93 


1.79 


Low 


1.98 


0.86 


1.70 


High 


1.82 


0.70 


1.27 


High 


1.98 


0.74 


1.46 


Low 


1.78 


0.19 


0.33 


High 


1.92 


0.98 


1.88 


High 


1.96 


1.32 


2.58 


High 


(1.91) 


0.40 


0.76 


Low 


1.73 


1.01 


1.74 


High 


1.87 


0.90 


1.68 


High 


(191) 


0.99 


1.89 


Low 


1.89 


1.06 


2.00 


Low 


1.86 


1.50 


2.79 


High 


1.74 


1.18 


2.05 


Low 


2.42 


1.07 


2.58 


High 


1.81 


0.37 


0.66 


High 


(191) 


0.46 


0.87 


Low 



* S prefix for Surveyor stations; P prefix for Pioneer stations. 



6242 



BURNS AND GRIM 



area. These measurements are not evenly dis- 
tributed and can be discussed by considering a 
subdivision based on spatial grouping. 

Eastern Part of Continental Rise 

This subdivision covers the eastern parts of 
the Delgada and Monterey fans and is arbi- 
trarily defined as being east of the 4,000-meter 
isobath (see Figure 1). Earlier measurements 
from this region indicated a relatively high heat 
flow ((Q) = 2.2 jucal cm" 2 sec" 1 ) with low spatial 
variability. These earlier stations are clustered 
in a relatively small portion of the area, and one 
of the objectives of the present investigation 
was to determine whether they are representa- 
tive of this part of the continental rise. Conse- 
quently, additional heat flow measurements 
were made at stations P-12, P-13, P-15, P-16, 
S-6, S-7, S-8, S-21, S-22, and S-23. The mean 
regional heat flow estimated from the data ob- 
tained at these ten stations is 1.7 iical cm" 2 sec" 1 
(s = 0.2 tical cm" 2 sec" 1 ), and, if the previous 
data are included, the mean is 1.8 /teal cm -2 sec" 1 
(s = 0.3 jucal cm -2 sec" 1 ) . 

From these estimates, heat flow in the eastern 
part of the continental rise, as defined here, 
appears to be slightly high (<Q) = 1.7 to 1.8 
/xcal cm" 2 sec" 1 ), and the spatial variability is 
low enough to permit acceptance of the mean 
as a representative estimate of the regional flow 
through the present sea floor. The low vari- 
ability in this part of the UMP area is likely 
to be caused, at least in part, by the thick 
accumulation of sediment and consequent lateral 
near-homogeneity of thermal conductivity in the 
Delgada and Monterey fans. 

Considering the area, volume, and age (10 7 to 
4 X 10 7 years) of the fan deposits [Menard, 
1964], we can estimate an average sedimenta- 
tion rate of 1 to 7 X 10" 3 cm/yr. At this rate, 
the pre-existing (subsedimentary) regional heat 
flow would be from 2 to 10% higher than the 
presently measured heat flow, which is already 
significantly higher than the world average of 
about 1.5 /xcal cm" 2 sec" 1 [Lee and Uyeda, 1965]. 

Western Part of Delgada and 

Monterey Fans 

Prior to the UMP, five scattered measure- 
ments (see Figure 1) had been taken from the 
western part of the Delgada and Monterey fans. 
These measurements have a mean of 1.7 /xcal 



cm" 2 sec" 1 but are extremely variable (s = 1.2 
/teal cm" 2 sec" 1 ). One of the basic objectives of 
the UMP work was to determine if this vari- 
ability was representative of this part of the 
area (as contrasted with the small variability 
over the eastern part of the continental rise) 
and to attempt a relatively detailed investi- 
gation of a profile {A- A' in Figure 1) between 
the two previously published strongly contrast- 
ing high and low heat flow values (3.45 and 
0.6 ^cal cm" 2 sec" 1 ) mentioned above. 

Of the fifteen additional stations taken over 
this part of the fan deposits, twelve were along 
A-A' (P-10, P-17, P-18, P-20, P-21, P-22, S-9, 
S-10, S-12, S-16, S-19, and S-20) and three 
(P-3, S-24, and S-25) were taken as scattered 
stations off the profile. In aggregate, these 
clearly indicate the absence of any consistent 
regional heat flow over the western part of the 
fan deposits. 

Geophysical profile. Although some previous 
studies (see, for example, Lister [1963] and 
Lachenbruch and Marshall [1966]) have ex- 
amined closely spaced heat flow measurements, 
the measurements along profile A-A' are more 
closely spaced than most and have additional 
geophysical measurements associated with them. 
Although the data along A-A' were not obtained 
concurrently, the use of satellite navigation dur- 
ing the UMP program reduces the positional 
uncertainty to well within the limits of the 
positions indicated in Figure 1. 

Figure 2 shows heat flow, total magnetic in- 
tensity, and topography for line A-A', and 
magnetic intensity and topography obtained 
during the UMP survey for lines B-B', C-C, 
and D-D' (see Figure 1 for locations). 

Topography. The western part of A-A' and 
B-B' are over the sediment-filled trough south 
of the Pioneer ridge [Menard, 1960], in what 
appears to be a narrow part of the abyssal plain 
extending in an east-west direction parallel to 
the Pioneer ridge [Menard, 1964]. The western 
part of D-D' is clearly south of the abyssal 
plain, as shown by its relatively rough topog- 
raphy. In general, the topography does not have 
any clearly defined continuity of north-south 
ridges or troughs in the area of A-A', which may 
be characterized as over abyssal plain at the 
west and on the fan deposits to the east. It 
should be noted that the western end of A-A' is 
clearly south of the Pioneer fracture zone. 



HEAT FLOW IN PACIFIC OCEAN 



6243 




Fig. 2. Heat flow along profile A-A' is shown together with the topography and total mag- 
netic field along profiles A-A', B-B', C-C, and D-D'. 



Magnetics. Two relatively prominent mag- 
netic anomaly bands can be seen in Figure 3. 
To the west, an anomaly band (indicated as 
la, 16, Ic, Id) characterized by a complex peak 
has continuity in a north-south direction. At the 
east, a second anomaly band (indicated as Ila, 
116, and lid) also appears to have continuity 
through the area. Figure 3 shows the apparent 
correlation of magnetic peaks and troughs 
across the sections A-A', B-B', C-C, and D-D'. 

Each of these anomaly bands is clearly shown 
by Mason and Raff [1961]. They indicate the 
north-south trend of anomaly I and show 



anomaly II trending northwest-southeast over 
a distance of 80 to 100 km. In addition to these 
two prominent anomaly bands, a less promi- 
nent one appears to be situated at Ilia, III6, 
IIIc, and Ma', but this band is not clearly de- 
fined on the Mason and Raff map. 

Heat flow. The section along A-A' indicates 
a general increase in heat flow from west to 
east. Considering the large variability char- 
acterizing this section, the UMP measurements 
agree well with the basic trend implied by the 
two earlier values reported by Von Herzen 
[1964] and Foster [1962]. In addition to the 



6244 



BURNS AND GRIM 




Fig. 3. Correlation of magnetic anomalies along profiles A-A', B-B', C-C, and D-D'. They 
are identical to those shown in Figure 2 but are arranged differently. Each profile is north of 
the one below it. Since A-A' crosses over C-C, as shown in Figure 1, it is split. There is a 
vertical offset of 200 gammas between profiles. The scales for the eastern part of A-A', C-C, 
the western part of A-A', and B-B' are obtained by subtracting 200, 400, 600, and 800 gammas, 
respectively, from the scale shown, which is for D-D'. 



general trend, there appear to be smaller scale 
variations that have sharp peaks and shallow 
troughs. 

One of the first questions to be asked is 
whether the implied regional gradient is real. 
The alternative to a regional gradient would 
be to assume a regional mean and to examine 
the observed values in terms of such effects as 
erosion-sedimentation, lateral variations of ther- 
mal conductivity, and secondary heat sources. 
The mean value of the heat flow measurements 
along the section (1.6 /xcal cm" 2 sec" 1 ) is com- 
parable to that estimated for the eastern part 
of the continental rise (1.7-1.8 jucal cm" 2 sec" 1 ), 
but the contrasts along the section are such that 
only an extremely arbitrary assignment of the 
effects mentioned above can force a regional 
mean into any approximation of the observed 
values. 

On the other hand, if the regional gradient 
exists, the observed values of heat flow may be 
examined in terms of departure from the re- 
gional field. The basic constraints on any ap- 
proximation of a regional gradient along section 
A -A' are (1) the observed values of heat flow 
along the section, (2) that the eastern end 
should be comparable to the regional mean 
observed over the eastern part of the con- 
tinental rise (1.7-1.8 jucal cm" 2 sec" 1 ), and (3) 
that the western end should not be unrealisti- 
cally less than a representative oceanic mean 
(about 1.0 jucal cm" 2 sec" 1 ). 



The observed heat flow values from section 
A-A' have been subjected to least-square fits for 
first- through twelfth-order polynomials. A re- 
gional smooth field is apparent through the 
fourth order but is increasingly obscured by 
shorter wavelength influences at fifth and 
higher orders. In view of constraints 2 and 3, 
both the third and the fourth order indicate a 
physically acceptable approximation of a re- 
gional smooth field, and there is no basic differ- 
ence between them in terms of local departure 
of the individual station values of heat flow. 

The regional field determined by the fourth- 
order polynomial (Figure 4) indicates the pos- 
sibility of systematic distribution of heat flow 
repeating over a 'wavelength' of several hun- 
dred kilometers. This appears to be compatible 
(in both sense and magnitude) with the physical 
constraints (2 and 3, above) and the conclu- 
sions reached by Von Herzen [1964] in regard 
to apparent 'banding' of high and low heat flow 
in this part of the Pacific. If such a regional 
gradient is present over the distance covered by 
section A-A', the heat flow 'anomalies' (Figure 
4) have an absolute contrast of a magnitude 
that can be explained by physically realistic 
assumptions in regard to modifications in the 
smooth regional field by surface and near sur- 
face effects. 

A fourth-harmonic Fourier fit has been made 
to the heat flow data from section A-A', assum- 
ing a fundamental wavelength in the regional 



(0 

5'o 



3 8 






4.0 



3.0 



\- e 2.0 

< o 
UJ v. 



1.0 



HEAT FLOW IN PACIFIC OCEAN 



6245 



A' 





• 


1 


1 1 


1 1 


! 




1 

VH 

D 












A 






A 




— 






REGIONAL HEAT 
FLOW CURVE "A 

Jr" 


-^ • 


o 


A 




t 


F 

a 




• 
1 


1 1 


1 1 


1 




1 






20 



40 60 80 100 120 

DISTANCE IN KILOMETERS 



140 160 



Fig. 4. Heat flow values along A-A' are shown at the top with a regional heat flow curve 
obtained with a fourth-order least-squares polynomial fit. The bottom section shows the 
'anomalies' obtained by subtracting the regional curve from the observed values. 



field of 260 km (estimated from Figure 4) . The 
computed and observed heat flow values along 
section A-A' are shown in Figure 5. In addition 
to providing a closer fit to the basic data than 
the smooth field of the fourth-order polynomial 
(Figure 4), the Fourier fit strengthens the con- 
clusion that shorter length variations of heat 
flow are actually superimposed on the regional 
field. The wavelength of these variations may be 
estimated from either Figure 4 or Figure 5 and 
is approximately 50 km. 

In general, both the heat flow anomalies and 
the Fourier analyses indicate that the heat flow 
at stations P-17, VH, and P-20 is clearly above 
the regional; stations S-9, P-18, S-20, S-10, 19, 
P-21, and S-12 are low. Both analyses also 
indicate a slight localized high value associated 
with station S-16, which is neither strong nor 
well defined, and an indication of a slightly high 
value at station F with further increase im- 
plied to the west. 

Discussion. One of the more striking geo- 
physical characteristics in this region of the 
Pacific is the north-south trend of magnetic 
anomaly bands [Mason and Raff, 1961; 
Vacquier et al., 1961; Raff and Mason, 1961]. 
Although possible local associations of heat 



flow variability with these magnetic lineations 
has been considered by Von Herzen [1964], his 
data spacing did not permit identification of 
variations in heat flow with wavelengths com- 
parable to the magnetic anomalies. If the 50-km 
wavelength implied by the heat flow data along 
section A-A' is real, however, the wavelengths 
of the magnetic and the heat flow anomalies are 
of comparable magnitude in this general area. 
Because of their size, the heat flow anomalies 
will have to be examined with more closely 
spaced measurements to define the size and 
depth of their sources. However, even the exist- 




20 40 60 80 100 120 140 160 

DISTANCE IN KILOMETERS 

Fig. 5. A fourth-harmonic Fourier fit of heat flow 
data along A-A'. 



6246 



BURNS AND GRIM 



ing data indicate the presence of relatively 
shallow sources for the high heat flow anomalies, 
and the range of sizes and of depths of sources 
that can be fitted to these data is within the 
size and depth ranges proposed for the sources 
of the positive magnetic anomalies (see, for 
example, Mason and Raff [1961]). 

Other UMP Heat Flow Measurements 

Stations S-l and S-14 were taken along the 
general trend of section A-A' extended to the 
west. Both indicate relatively low heat flow 
(0.6 and 0.5 /xcal cm" 2 sec" 1 ) but cannot be 
considered with the data from along A-A', since 
they are not south of the Pioneer fracture zone. 

Stations S-2, S-3, S-4, and S-5 were taken to 
fill the open part of the UMP area along lati- 
tude 35°30 / N. They form a reconnaissance sec- 
tion along the parallel, are generally high, and 
have very high variability. One extremely high 
value (4.6 /teal cm" 3 sec" 1 ) was measured at 
S-3, and an average value (1.6 jucal cm" 2 sec" 1 ) 
was measured at S-4. As in the case of section 
A-A', the absolute contrasts here are too large 
to explain in terms of a simple regional mean, 
but the data available are too few for any 
pertinent analyses for regional gradients and 
heat flow anomalies. 

Summary and Conclusions 

Heat flow data from the eastern part of the 
continental rise before the Upper Mantle 
Project indicated a relatively constant heat flow 
over this part of the UMP area, but the data 
were spotty. The additional measurements re- 
ported here indicate that there is very little 
departure from the regional mean of 1.7 to 1.8 
jttcal cm" 2 sec" 1 over this part of the continental 
rise. 

Very strongly contrasting high and low heat 
flow values and an implied banding over a 
wavelength of several hundred kilometers were 
suggested by the pre-UMP data over the off- 
shore parts of the UMP area. These general 
characteristics have been verified by the addi- 
tional measurements. 

Section A-A', which is the only section con- 
taining reasonably close-spaced data, appears to 
be on the flank of longer wavelength of high 
and low heat flow which have a fundamental 
wavelength of about 260 km. The regional 
gradient along the section is from high heat 



flow at the east (comparable with the regional 
mean of the eastern part of the continental 
rise) to low heat flow at the west. 

In addition to a regional field, the data from 
section A-A' indicate a shorter wavelength varia- 
tion in heat flow with a wavelength of about 
50 km. This appears to be attributable to local- 
ized high and low heat flow superimposed on 
the regional trend. By treating the observed 
heat flow as anomalies from the regional field, 
the absolute contrast of the data is reduced to 
a magnitude that may be explained by physi- 
cally realistic models of such effects on the re- 
gional field as are caused by nonhomogeneous 
thermal conductivity, erosion-sedimentation, 
and supplementary shallow heat sources. 

Acknowledgments. We wish to thank the offi- 
cers and crew of the U. S. Coast and Geodetic 
Survey ships Pioneer and Surveyor and especially 
William Lucas, who assisted in making the heat 
flow measurements. We have benefited from dis- 
cussions with C. R. B. Lister and J. C. Kelley, and 
received help and advice on various aspects of this 
study from T. V. Ryan and W. Anikouchine. 

References 

Bullard, E. C, and A. Day, The flow of heat 
through the floor of the Atlantic Ocean, Geo- 
phys. J., 4, 282-292, 1961. 

Foster, T. D., Heat-flow measurements in the 
northeast Pacific and in the Bering Sea, J. 
Geophys. Res., 67, 2991-2993, 1962. 

Gerard, R., M. G. Langseth, Jr., and M. Ewing, 
Thermal gradient measurements in the water 
and bottom sediment of the western Atlantic, 
J. Geophys. Res., 67, 785-803, 1962. 

Lachenbruch, A. H., and B. V. Marshall, Heat flow 
through the Arctic Ocean floor: The Canada 
basin-Alpha rise boundary, J. Geophys. Res., 
71, 1223-1248, 1966. 

Langseth, M. G., Techniques of measuring heat 
flow through the ocean floor, in Terrestrial Heat 
Flow, Geophys. Monograph 8, edited by W. H. 
K. Lee, pp. 58-77, American Geophysical Union, 
Washington, D. C, 1965. 

Langseth, M. G., P. J. Grim, and M. Ewing, Heat- 
flow measurements in the east Pacific Ocean, 
J. Geophys. Res., 70, 367-380, 1965. 

Lee, W. H. K., and S. Uyeda, Review of heat-flow 
data, in Terrestrial Heat Flow, Geophys. Mono- 
graph 8, edited by W. H. K. Lee, pp. 87-190, 
American Geophysical Union, Washington, 
D. C, 1965. 

Lister, C. R. B., A close group of heat-flow sta- 
tions, J. Geophys. Res., 68, 5569-5573, 1963. 

Mason, R. G., and A. D. Raff, Magnetic survey off 
the west coast of North America, 32°N latitude 
to 42°N latitude, Bull. Geol. Soc. Am., 72, 1259- 
1266, 1961. 



HEAT FLOW IN PACIFIC OCEAN 



6247 



Menard, H. W., Possible pre-Pleistocene deep-sea 
fans off central California, Bull. Geol. Soc. Am., 
71, 1271-1278, 1960. 

Menard, H. W., Marine Geology of the Pacific, 
McGraw-Hill Book Company, New York, 1964. 

Raff, A. D., and R. G. Mason, Magnetic survey 
off the west coast of North America, 40 °N lati- 
tude to 52°N latitude, Bull. Geol. Soc. Am., 72, 
1267-1270, 1961. 

Vacquier, V., A. D. Raff, and R. E. Warren, 
Horizontal displacements on the floor of the 



northeastern Pacific Ocean, Bull. Geol. Soc. Am., 
72, 1251-1258, 1961. 

Von Herzen, R. P., Ocean-floor heat-flow measure- 
ments west of the United States and Baja Cali- 
fornia, Marine Geol., 1, 225-239, 1964. 

Von Herzen, R. P., and S. Uyeda, Heat flow 
through the eastern Pacific Ocean floor, J. Geo- 
phys. Res., 68, 4219-4250, 1963. 



(Received June 27, 1967.) 



11 



Reprinted from YEARBOOK OF SCIENCE AND TECHNOLOGY, McGraw-Hill, New York 



Astrobleme 

The search for astroblemes, ancient meteorite- 
impact scars on the Earth, has intensified in re- 
cent years. Interest is keen because the Moon is 
presumably covered with such scars, and several 
large Quaternary meteorite craters have been 
found on the Earth's surface. About 50 probable 
examples of terrestrial astroblemes have been 
identified to date, but at none of them has meteor- 
itic material been found, except in connection 
with the meteorite craters of geologically recent 
date. Even so, the geological record of pre-Quater- 
nary time might be expected to include numerous 
impact scars even though erosion has occurred 
since they were formed. 

The larger Quaternary meteorite craters, both 
definite and probable, are the following, arranged 
in order of size from about 1 km to 10 km in di- 
ameter: Pretoria Salt Pan Crater, South Africa; 
Meteor (Barringer) Crater, Arizona; Talemzane, 
North Africa; Lonar Crater, India; Roter Kamm, 
Southwest Africa; New Quebec Crater, northern 
Canada; and Bosumtwi Crater, Ghana. The 
15,000,000-year-old (latest Miocene) Ries Basin 
structure in West Germany may be regarded as a 
feature transitional between a meteorite crater 
and an astrobleme because its craterlike appear- 
ance is not fully erased. All the basic shock cri- 
teria for astroblemes are found at the Ries Basin. 




Fig. 1 . A shatter cone in limestone from the Kent- 
land, Ind., astrobleme. 



110 Astrobleme 




Fig. 2. Photomicrographs, magnified about 40 
times, of (a) normal unfractured Coconino sandstone 
and (b) its shock-fractured equivalent from Meteor 
(Barringer) Crater, Ariz. Rhombohedral sets of planar 

In addition, meteoritic spherules in silica glass, 
but not ponderable meteorites, are present. 

Criteria. The term cryptoexplosion structure 
pertains to a highly disturbed geological feature 
resulting from a natural explosion of uncertain 
cause. Such structures are fairly common, but 
only some of them appear to be astroblemes. 
Others are generally believed to be cryptovolcanic 
structures caused by phreatic (steam) or volcanic 
explosions but without the extrusion of volcanic 
products or hydrothermal alteration. 

The distinctive hallmarks of astroblemes result 
from intensive shock-wave damage to the rocks. 
At least four types of criteria are now generally 
recognized. First is the presence in the rock for- 
mations of a distinctive type of conical fracture, 
called shatter cones, which display striated mark- 
ings like "horsetails" (Fig. 1). These are apparently 
the result of shock fracturing and therefore seem 
to be a useful criterion. Second is the presence of 
shock-induced polymorphs of silica or feldspar, 
such as coesite, stishovite, and maskelynite. Third 
is the occurrence of shock-induced microfractur- 
ing of crystals whereby, for example, certain planar 
sets of fracture appear in quartz (Fig. 2) and biotite 
becomes kink-banded. The fourth criterion is the 
presence of lechatelierite, high-temperature silica 
glass. 

Discoveries. Putative astroblemes contain one 
or more of the above criteria. Seventeen are now 
known from shatter coning alone. This is often 
the first hallmark to be identified as it is a field 
criterion rather than a laboratory one. The Stein- 
heim Basin, a twin structure to the Ries Basin 
formed at the same time, is the prototype shatter- 
coned structure. The Wells Creek Basin structure 
in Tennessee (Fig. 3) is an example of shatter- 
coned structure in the United States. The geolog- 
ical plan shows that the typical damped-wave 
form is created. A central dome is surrounded 
by a ring syncline and a ring anticline. Other 
shattcr-coned structures in the United States 
are Sierra Madera in Texas, Kentland in Indiana, 
Serpent Mound in Ohio, Decaturville and Crooked 
Creek in Missouri, and Flynn Creek in Tennessee. 



fractures are seen in the quartz grains, between 
which is silica glass containing coesite and stishovite, 
all created by shock waves from a meteorite impact. 
(NASA) 




uncertain 
fault extension 



scale in miles 
J St. Louis formation 



J Warsaw-Fort Payne formation 
2 Hermitage to Chattanooga formations 
_] Stones River formation 
h| Knox formation 

Fig. 3. Geologic map of Wells Creek Basin struc- 
ture in Tennessee, a putative astrobleme. (R. Stearns 
and H. Tiedeman, Vanderbilt University) 

During 1965, a new shatter-coned structure was 
identified, the Middlesboro Basin structure in 
Kentucky. 

A highly interesting probable new astrobleme, 
although regarded by Australian geologists T. 
Quinlan and C. E. Prichard as a diapir, is Gosses 
Bluff, 150 mi west of Alice Springs in central 
Australia in the Amadeus Basin geosyncline. 
Lower Paleozoic and Proterozoic strata are in- 
volved in the deformation of this 2-mi-diameter 
circular uplift. The structure must have about a 
6-mi diameter overall, but the outer portion is 



Astrogeology 111 



hidden beneath desert alluvium. The astrobleme 
identification is based upon the definitive presence 
of shatter cones. The structure promises to do 
much to unravel the nature of cryptoexplosions 
as many types of beds are affected rather than 
only carbonates, which rarely show shock effects 
other than shatter cones. The structure has 
been test-drilled to more than 3000 ft, and the 
incompetent Bitter Springs limestone, supposedly 
the active bed which flowed into a plug to form the 
supposed diapir, was not encountered. 

Recently shatter cones have been discovered 
by E. L. Krinov in the main crater of the Kaalijarv 
meteorite crater group in Estonia. 

For background information see ASTEROID; 
METEORITE in the McGraw-Hill Encyclopedia of 
Science and Technology. 

[r. s. dietz) 

Bibliography: N. L. Carter, Am. J. Sci., 263: 
786-806, 1965; R. S. Dietz, Meteoritics, 3(1): 
27-29, 1966. 



12 



Reprinted from MEDICAL OPINION AND REVIEW Vol. 3, No, 1 



':>^k,'i^V-'Tr f : ' % \ ..,.-... .^ 



















Science: 

Craters and Legends 

Roberts. Dietz, Ph.D. 





Meteor Crater, Arizona 



On four mornings last November 
I spent the early predawn twilight 
on the rim of Arizona's Meteor 
Crater, observing the Ikeda-Seki 
sun-grazing comet through a Ques- 
tar telescope. I had traveled there 
from the annual Metcoritical So- 
ciety meeting at Odessa, Texas, with 
Richard Barringer, son of D. Mor- 
eau Barringer. It was the elder Bar- 
ringer who, at the turn of the cen- 
tury, first recognized Meteor Crater 
as the site of a giant meteorite ex- 
plosion in the recent geologic past. 
He was so intrigued by this yawn- 



Robeht S. Diktz is a Research 
Occanographer witJi the US Coast 
and Geodetic Survey in Washing- 
ton, DC 



ing hole in the ground that he spent 
the last twenty-five years of his life 
(from 1903 to 1927) attempting to 
mine the great meteorite he as- 
sumed lay buried beneath the crater 
floor— a heroic venture fraught with 
difficulties and disappointment, and 
unique in mining annals. The Bar- 
ringer family still maintains the 
crater as a public trust and fosters 
research in the field of meteorities. 
It seemed to me singularly appro- 
priate to be observing this spectacu- 
lar comet from the rim of a crater 
created in a flaming instant 25,000 
years ago by the impact of another 
celestial object. Meteorite craters 
are rare geomorphic forms; only 
about a score are known from all 
over the world, so we are fortunate 



50 



in having the finest example on na- 
tive soil. There is only one other 
meteorite crater here in the United 
States. It is near Odessa, Texas, and 
it was the reason for the convening 
of the Meteoritical Society meeting 
there. The Odessa site is small and 
it has been badly despoiled Since its 
discovery in 1932. But recently a 
group of public-spirited citizens of 
Odessa have restored the site, and 
its future as a fascinating natural 
feature is now assured. 

The list of large (more than 3,000 
feet in diameter) meteorite craters 
of the world is short, even including 
probable as well as definite exam- 
ples. They are, in order of increas- 
ing size: Pretoria Salt Pan in South 
Africa, 3,400 feet across; Meteor 

Medical Opinion & Review 



Crater in Arizona, 4,000 feet across; 
Talemzane in North Africa, 5,600 
feet across; Lonar Crater in India, 
6,000 feet across; Roter Kamm Cra- 
ter in Southwest Africa, 8,000 feet 
across; New Quebec ( Chubb ) Cra- 
ter in northern Canada, 11,300 feet 
across; and the Ashanti Crater in 
Ghana, 33,000 feet across. Some 
smaller meteorite craters that are of 
exceptional interest because of as- 
sociated mcteoritic debris are the 
Ilenbury, Boxhole, and Wolf Creek 
Craters in Australia; the Wabar 
Craters in Arabia; and the just-dis- 
covered Monturaqui Crater in 
northern Chile. 

Moon, Mars 

Scientific interest in meteorite 
craters has, recently been stimulated 
by the prospect of man landing on 
the Moon. The controversy on the 
volcanic versus meteoritic origin of 
lunar craters has now run its course, 
with a clear victory for the theory 
of creation by impact. Mars, too, is 
covered with impact craters, as was 
recently shown by photos from the 
Mariner IV fly-by. This greatly en- 
hances interest in the few meteorite 
craters on Earth. Astronauts already 
receive some of their training at 
Meteor Crater, and we can expect 
intensive scientific study of all sites 
that provide clues to the lunar ter- 
rain. 

Meteor Crater, seen from the ap- 
proaching highway, looms across 
the desert as a flat-topped mesa, 
giving no hint of the great hole in- 
side. This silhouette is actually the 
crater's upturned rim, rising 170 
feet above the surrounding dry 
russet plain and containing 300 mil- 
lion tons of fragmented rock. The 
crater it circumscribes is nearly a 
mile across and 600 feet deep. 
About 25,000 years ago, an errant 
cosmic body, presumably from the 
asteroid belt between Mars and 
Jupiter, zeroed in on the Earth. 
Coming in from the north, a huge 
nickel-iron mass of perhaps a quar- 
ter-million tons traveling at about 



ten miles per second, so that each 
ounce of meteorite had 400 times 
the energy of a high-speed bullet, 
struck the ground. In a blinding 
flash of light, the meteorite bored 
into the solid rock, causing a ten- 
megaton explosion. Under the enor- 
mous percussion, the meteorite be- 
haved as though it were fluid. It 
flattened, turned inside out, and 
swept rock debris outward and up- 
ward—leaving a paraboloid crater 
like those on the moon. Rocks as 
big as cottages were hurled for a 
quarter of a mile. Part of the mete- 
orite was converted into a vapor 
that mixed with Earth debris, rose 
into the stratosphere as a mushroom 
cloud, and rained down minute me- 
teoritic droplets that can still be 
found in the surrounding country- 
side. 

White men first learned about 
Meteor Crater in 1871, but they 
thought it was just another volcanic 
(rater. It was already familiar to the 
Navajo and Ilopi Indians of the re- 
gion. The Ilopi tribe used to gather 
the finely powdered white silica— 
Coconino sandstone crushed into 
"rock flour" by the force of the im- 
pact—to use in their ceremonies. 

In 1891, a prospector in the region 
discovered "nuggets of silver" that 



on examination proved to be nickel- 
iron meteorites. They were chris- 
tened Canyon Diablos, after the 
principal river in the area, but their 
direct association with the crater 
went unrecognized at first. Never- 
theless, they achieved immediate 
international fame when they were 
found to contain diamonds, even 
though the stones were carbonados 
or black diamonds, not the precious 
variety. Diamonds are, of course, 
the hardest known natural sub- 
stance in existence. Their presence 
was detected when an attempt was 
made to cut a nugget. The cutting 
disk abruptly stopped working, and 
its teeth were stripped down to a 
nubbin when they struck a nest of 
minute diamonds. 

We now believe that these dia- 
monds were formed instantaneous- 
ly as the shock of impact on the 
Earth converted the mineral cohen- 
ite ( an iron carbide ) into the high- 
pressure polymorph of carbon we 
call diamond. Canyon Diablos are 
the only diamondiferous nickel-iron 
meteorites known, although there 
are at least three other stony mete- 
orites that contain diamonds. These, 
too, are thought to be shock-created, 
but by impacts in space, not on 
the Earth. Ordinary terrestrial dia- 




Meteorite Crater, Odessa, Texas 



January. 1967 



51 



monds are of quite a different gene- 
sis, formed by static high pressures 
in the Earth's upper mantle. They 
are carried to the surface through 
kimberlite pipes that, in places like 
South Africa, have bored their way 
through the Earth's granitic crust. 

All meteorites are highly prized 
by scientists. They are rare samples 
of the cosmos that give us some ink- 
ling of the nature of the sun and the 
other planets. Curiously, it was by 
determining the age of Canyon 
Diablo meteorites from the ratio of 
their lead isotopes, which provide 
a radiometric "clock," that Califor- 
nia Institute of Technology scien- 
tists first inferred the Earth is 4.5 
billion years old. They found the 
meteorites to be older than any 
rocks known on Earth and, as the 
Earth rocks have been subjected to 
many changes, they reasoned that 
the Canyon Diablos are primitive 
substances representing the true age 
of both the solar system and the 
Earth. 

The attempt to mine the Canyon 
Diablo meteorite commercially for 
its riches failed. People did not real- 
ize that giant meteorites vaporize 
almost completely on impact. Find- 
ing meteoritic fragments at a mete- 
orite crater is about as difficult as 
finding TNT in a bomb crater; only 
about thirty tons of Canyon Diablos 
have ever been recovered. Before 
his death, however, D. Moreau Bar- 
ringer did succeed in establishing 
the meteorite impact origin of Me- 
teor Crater, over the objections of 
the two renowned United States 
Geological Survey geologists G. K. 
Gilbert and N. H. Darton, who con- 
tended that the crater was blasted 
out by a steam explosion, a sort of 
incipient volcanism. 

Of all the world's meteorite cra- 
ters, Meteor Crater is the best pre- 
served, the most elegant, and the 
most accessible. It is visited by 
150,000 tourists a year and is one of 
the world's most remarkable natural 
wonders. Svante Arrhenius, a Swed- 
ish Nobel Laureate in chemistry, 




Meteorite in situ 

once described it as "the most fas- 
cinating spot on Earth." 

Another meteorite crater is the 
twin Wabar ( actually there are two 
meteor craters) discovered by the 
explorer H. St. J. Philby, who tra- 
versed Arabia's Empty Quarter 
(Rub 'al Khali) in 1932. He was 
searching for the legendary ruined 
city of Wabar, supposedly de- 
stroyed by fire and brimstone like 
Sodom and Gommorah, and for a 
legendary chunk of native iron 
called Al Hadida ( the lump of iron ) 
allegedly "as big as a camel." But let 
Philby tell the story: 

"We marched on till the ruins 
came into sight, a long black wall, 
as it seemed, riding on the sands. 
We drew nearer and halted at a 
suitable camping spot, while I im- 
mediately hastened to the top of a 
low sand-hill nearby to get a good 



first view of the site before dark. 
The great moment had at last ar- 
rived, the moment I had longed for 
for fourteen years, and 1 found my- 
self looking down on the ruins of 
what appeared to be a volcano! So 
that was Wabar. the city of a wicked 
king, destroyed by fire from heav- 
en and thenceforward inhabited 
only by semi-human monomem- 
brous monsters. A volcano in the 
midst of the Bub 'al Khali! And be- 
low me, as I stood on that hill-top 
transfixed, lay the twin craters, 
whose black walls stood up gauntly 
above the encroaching sand like the 
l>attlements and bastions of some 
great castle. These craters were re- 
spectively about 100 and 50 yards in 
diameter, sunken in the middle but 
half choked with sand, while inside 
and outside their walls lay what I 
took to be lava in great circles where 
it seemed to have flowed out from 
the fiery furnace. Further examina- 
tion revealed the fact that there 
were three similar craters close by, 
though these were surmounted by 
hills of sand and recognizable only 
by reason of the fringe of blackened 
slag round their edges. 

"My companions were soon busily 
engaged in digging into the ruins 
for treasure, and nothing I said 
could stop them. Their saddle-bags 
were soon filled to bursting with the 
little jet-black shining pellets which 




■-■ 
Wabar Crater, Arabia 



January, 1967 



53 



strewed the place and which they 
took for pearls, the pearls of the 
numerous ladies who, according to 
the tradition, had graced the court 
of King 'Ad and perished in the 
flames. Two months later these 
relics were going around the mar- 
ket at Mecca leaving disappoint- 
ment in their train, but to this day 
my companions believe that the 
ruins we saw were indeed the ruins 
of a great city. Yet the truth is that, 
after all we had already seen of flint 
implements and other evidences of 
ancient man, this locality failed to 
produce the slightest vestige of 
human occupation, temporary or 
otherwise, modern or ancient. The 
nearest water was ten miles away 
at Faraja, and the river I had hoped 
to find was nowhere to be seen. The 
secret of Wabar was out at last, and 
all that remained to do was to search 
for the iron 'as big as a camel.' It 
was like searching for a needle in a 
haystack, and I thought it best to 
leave my companions to it. 

Fragment 

"The party had to confess failure 
in their search. They had found a 
silly little fragment of iron, but it 
was not as big as a camel, so they 
had not worried about it. I sent 
somebody in search of it, and he 
duly brought it along. It was about 
the si/e of a rabbit, but I have very 
little doubt that it was the very 
thing we had come to find. Legend 
had magnified it as we still magnify 

fish The camel had gone through 

the eye of a needle with a ven- 
geance, but the meteorite ( for that 
is what it was ) will doubtless be of 
some interest to experts. It was im- 
mensely heavy, as the camels had 
good reason to know for the next 
month or more. So, for all practical 
purposes, we had found the iron 
and we had found the ruins. The 
two localities had merged into one." 
( From Geographical Journal, 1933. ) 

Subsequent history has proved 
Philby somewhat mistaken. Recent- 
ly Thomas Abcrcrombie of the Na- 






1 




tional Geographic Society found a 
5,000-pound nickel-iron meteorite at 
Wabar (National Geographic, Jan- 
uary, 1966). This is certainly Al 
Hadida— the lump of iron "as big as 
a camel." One is reminded of an old 
Arab proverb: "There are three 
things impossible to hide: smoke, 
a man riding a camel, and love be- 
tween two people." The proverb 
seems not to apply to a meteorite 
as big as a camel amidst the shifting 
sands of the trackless Empty Quar- 
ter. 

Lonar Crater in India is still an- 
other crater most likely caused by 
a meteor. It has all the character- 
istic features except for any known 
associated meteoritic debris. A 
splendid, perfectly circular natural 
feature 6,000 feet across and 600 
feet deep, it is rich with wild fowl 
and archeologic sites. A spring-fed 
brackish lake lies in the middle, 
while around the shore are fourteen 
ancient temples. The lake has slow- 
ly risen over the past 100 years, until 
some of the houses of worship are 
knee-deep in water. 

Prior to my study of the crater, 
Indian geologists had simply con- 
sidered it to be another volcanic ex- 
plosion crater. But plateau lavas of 
this type, like the Columbia basalts 
of western Washington, issued qui- 
etly from fissures without ever pro- 
ducing craters. And the Deccan 
traps ceased erupting 60 million 



Lonar Crater, India' 

years ago, whereas Lonar is obvi- 
ously young, not more than a few 
hundred thousand years old. Fur- 
thermore, it is regionally unique; 
the entire subcontinent of India, in- 
cluding even the lofty Himalayan 
Mountains, completely lacks any 
contemporary volcanism. Finally, 
vvc don't have to invoke rare chance 
to account for a meteorite striking 
the Deccan traps. These ancient 
lavas cover 250,000 square miles, so 
they offer a sizable target for a cos- 
mic bolide. 

Any thought of either volcanism 
or meteorite impact is quite foreign 
to the natives in the village of Lonar. 
According to local legend, this great 
crater was once the covered and 
m eluded den of a mad giant who 
ravaged the surrounding country- 
side. To counter the giant, the god 
Vishnu came down from Heaven 
and courted the giant's sister until, 
eventually, she revealed his hiding 
place. Vishnu forthwith tore the top 
off the den and threw it five miles 
away, where the lid may still be 
seen, preserved as a dome-shaped 
mountain. Then, in a bloody strug- 
gle, he slew the giant. The crater 
remains a remnant of this heroic epi- 
sode in Indian folklore. 

Lonar Lake is fed largely by a 
single gushing spring of cool, clear, 
and potable water that is also the 
sole water supply for the village of 
Lonar. Lithe women swarm to the 



January, 1967 



57 



spring all day long like a stream of 
ants, filling their water jugs and 
toting them back on their heads. 
The spring is regarded as holy. It is 
told that a fakir threw a stick into 
the sacred waters of the Ganges at 
Banaras, 500 miles to the northwest. 
He watched it disappear in a whirl- 
pool, then ran all the way back to 
Lonar, arriving just in time to see 
the very same stick issue from the 
spring. 

From my own studies, I am con- 
vinced that Lonar is a bona fide 
meteorite impact crater. It has many 
of the usual hallmarks by which we 
have learned to identify such cra- 
ters, including a raised rim with 
upturned, and locally flipped over, 
country rock, and drilling has re- 
vealed a nest of breccia (highly 
fractured and crushed rock) under- 
lying the crater floor. 

From the vast expanse of gently 
undulating bushveld located about 
twenty-five miles north of Pretoria, 
the capital of the Republic of South 
Africa, a low, tree-clad ridge of 
broken outline rises. To the surprise 
of the stranger approaching the 
ridge, he finds it encloses a perfectly 
circular depression that has a flat 
bottom covered with a dazzling 
white saline encrustation. Over-all, 
this remarkable crater is 3,500 feet 



across, 400 feet deep, and about two 
miles in circumference. 

One's immediate thought is that 
it is an ancient and extinct volcanic 
crater, but the entire bowl is im- 
pressed in granite and there is abso- 
lutely no sign of lava or any other 
products of volcanism. A dark, 
placid pool of soda-salt brine is in 
the center of the depression, mirror- 
ing the many-hued greenery of the 
inner slopes. This quiet pool and its 
white border present a striking sight 
not easily effaced from memory. It 
is especially impressive by moon- 
light, when somber shadows are 
cast by the bush-clad rim. Some 
abandoned mineworkings, about 
fifty years old, are scattered over the 
crater floor, relics of a brief episode 
during which common salt, trona, 
and other salts were recovered. 

Until quite recently this pan was 
the most important salt lick in the 
central Transvaal, and was visited 
by herds of game, including ele- 
phant. Before the advent of the 
white man it was a hunting ground 
for Bushmen, and remnants of their 
implements may still be found. 

Geologists originally thought the 
Pretoria Salt Pan was created by an 
explosion that had somehow es- 
caped from a deep-seated pool of 
molten rock. It is now widely ac- 




Pretoria Salt Pan 



ceptcd as meteoritic; it has all the 
hallmarks, although no meteoritic 
debris has ever been found. Drilling 
exposed a nest of crushed and frag- 
mented rock underlying the pan. 
The strata are upturned in a way 
that suggests a violent explosion of 
such an intensity that only a great 
meteorite; could have caused it. 

Residents 

A native family "occupies" the 
former manager's residence over- 
looking the pan. I say "occupies" 
advisedly. The members of the fam- 
ily actually live around a fire out in 
front, except when nightfall or rare 
inclement weather drives them in- 
doors. Even the term "indoors" is 
not quite appropriate; the doors, 
along with the windows and all 
other pieces of available wood, have 
been removed to feed the eampfire. 
So the natives have not entirely 
taken to the ways of the white man. 

Farther around the periphery I 
ran into a single native man with 
half a dozen boys living in a rude 
lean-to. At first they resented my 
presence, but eventually they ac- 
cepted it. The man finally told me 
he was running a coming-of-age 
school to teach the boys tribal mores 
and rites. When I told him of my 
meteorite impact theory for the 
crater's origin, he agreed that it was 
certainly correct— and he volun- 
teered the information that his kudu 
horn also came irom heaven. 

So there are perhaps a score of 
large meteorite craters on the Earth, 
which is not many compared to the 
Moon's 30,000 or so. But the Moon's 
surface is old and erosion there is 
nil, so its crust is a museum of an- 
cient geomorphic forms preserved 
in pristine beauty. Its surface is a 
counting plate recording all the cos- 
mic bolides that have struck over 
the last billion or more years. Me- 
teorite craters on Earth are short- 
lived. They don't last more than a 
million years, but they serve to re- 
mind us that Earth, too, is subject 
to cosmic bombardment. end 



58 



Medical Opinion & Review 



13 



Reprinted from SEA FRONTIERS Vol. 13 , No . 1 




Mid-ocean ridge. Slow convection currents in the mantle below are set in motion 
by the internal heat of the earth. It is these currents which some believe to have 
caused separation of the continents, leaving the mid-ocean ridge as a "scar." 



More A bout Continental Drift 



By Robert S. Dietz 

Institute for Oceanography 
Environmental Science Services Administration 

(Illustrated by John Holden) 

Because of readers' comments and interest in recent articles on continental 
drift, Sea Frontiers is pleased to present a fuller explanation of this contro- 
versial theory. 



These are times of scientific fer- 
ment. One of the great geologic 
debates now simmering argues the 
question whether the continents have 
been fixed in position throughout their 
history or whether they have drifted 
to their present locations. The cham- 



pions of the drift theory will eventual- 
ly be judged as either an avant garde 
or an idiotic fringe, depending on how 
the question is finally resolved. Fun- 
damental aspects of the earth's his- 
tory are involved, including the size 
and whereabouts of the ancient ocean 



66 



basins. So opinions are strongly op- 
posed and statements likely to be in- 
temperate. Reams of paper are being 
expended and gallons of ink spilled in 
this confrontation but the argument is 
now just warming up. 

Briefly, the debate is drawn along 
the following lines. The continental 
fixist believes that continents and 
ocean basins have always remained 
much as we see them today, anchored 
in position and with but minor mod- 
ifications of outline. This is the con- 
servative philosophy and American 
geologists have been raised in this 
tradition. Continental drifters, while 
disagreeing among themselves as to 
details, believe that all the continents 



were once either joined together into 
one universal continent called Pangaea 
or, more likely, organized into the 
northern hemisphere supercontinent of 
Laurasia and the southern hemisphere 
supercontinent of Gondwana. These 
great landmasses then broke into 
pieces and drifted apart 150 to 100 
million years ago. The case for Gond- 
wana is particularly strong. It is sup- 
posed to have been a single mass in- 
corporating the present continents of 
South America, Africa, Antarctica, 
and Australia; the subcontinents of 
India and Madagascar; and some 
"microcontinent" pieces such as the 
Seychelle Islands Bank and possibly 
the submerged Kerguelen Plateau, 



Reams of paper are being expended and gallons of ink spilled . . . but the argument 
is only just warming up. 







67 



both in the Indian Ocean, and perhaps 
other as yet undefined pieces. 

Compasses in Congealed Rocks 

Interest in drift has been aroused 
by rock magnetism or paleomagnetic 
studies which offered a new and inde- 
pendent approach to the drift problem 
(See K. M. Creer, "Continents on the 
Move," Sea Frontiers, Vol. 12, No. 3, 
May-June, 1966). When certain 
rocks, having magnetic properties, as 
in the case of basaltic lava flows, cool 
from the molten state at about 575° 
(through the Curie point), they retain 
the magnetism induced in them at that 
time by the earth's magnetic field. Thus 
the crystals in them become, as it were, 
frozen compasses, showing the earth's 
magnetic orientation and magnetic dip 
at the time of freezing. The horizontal 
direction of the magnetism in the rock 
points in the general direction of the 
earth's magnetic pole, just as in the 
case of a compass needle. In addition, 
the magnetic axis of the rock crystal 
dips downward towards the earth's 
magnetic pole, being vertical in rocks 
near the poles and decreasing its dip 
towards the equator, where the axis 
becomes horizontal. The "rock com- 
pass" gives information as to both 
latitude and orientation of the rock at 
the time its magnetism was frozen. 
Yatchsmen and sailors will see that the 
problem of determining the original 
longitude of those rocks remains un- 
solved — precisely as with marine navi- 
gation before John Harrison invented 
his chronometer. Only a line-of- 
position is obtained, not a fix. Never- 
theless, the changes in position of rocks 
shown by paleomagnetism provide 
rather convincing evidence that the 



continents today are not where they 
were 150 million years ago. In fact, 
most of these rock formations are not 
magnetized along the present-day di- 
rection of the earth's field, indicating 
they were somewhere else when they 
became magnetized. 

Thin Ocean Floor 

There are other reasons for believing 
that continents have been on the move. 
As a marine geologist, my own con- 
version to continental drift resulted 
from the numerous surprising discov- 
eries about the sea floor. The blanket 
of sediment on the sea floor, if it has 
thickened at a rate similar to that of 
present day sedimentation, would have 
a thickness related to the length of life 
of the ocean floor. If the ocean floors 
have always existed undisturbed, there 
would be a very thick layer of sedi- 
ment. Actually, it is surprisingly thin, 
indicating that the ancient ocean floor 
has been destroyed or reworked in 
some way. 

Another surprising fact is that, al- 
though the layer of granitic rock (sial) 
beneath the continents is very thick, 
it is entirely absent under nearly all 
of the deep sea, suggesting that the 
lighter granite of the continents, float- 
ing on the heavier mantle rocks below, 
was pulled apart when the continents 
separated, leaving the ocean crust bare 
of granite. Also, the rocks of the sea 
floor, as dated by their fossils or radio- 
metrically, are surprisingly young. 
Further, in the absence of erosion, 
mountains on the sea floor should last 
forever as they do on the moon, but 
we can find no very ancient seamounts 
beneath the sea. 

With the continental drift concept, 



68 



these and other surprises become the 
natural expectations. 

Fossil Evidence 

The fossils of Africa and South 
America indicate that, prior to 150 
million years ago, the same kinds of 
creatures existed on both continents. 
Subsequently, the evolution of life had 
already proceeded along quite differ- 
ent lines on the two continents. This 
suggests that the continents were orig- 
inally united and that free exchange 
of living creatures could take place, 
but that later they separated with both 
the continents and the evolution of life 
going their separate ways. Yet, most 
geologists remain skeptical of conti- 
nental drift. For example, to explain 
this faunal dispersion most fossil ex- 
perts find drift a sufficient explanation 
but not a necessary one. They argue, 
with unquestionable logic, that it is 
easier to drift a species than it is to 
drift a continent. Rafting long dis- 
tances at sea upon a floating log is 
one mode for such dispersion, and al- 
though such rafting would be a rare 
event, it is argued that, over the long 
sweep of geologic time, anything that 
might happen will happen. And, also, 
supposedly simpler than continental 



Most paleontologists claim that it is 
easier to explain the occurrence of sim- 
ilar species on continents widely sep- 
arated by the ocean on the basis of (top) 
transfer of living creatures by rafting on 
flotsam, by easy moves along ancient 
island chains, or by long subsided land 
bridges, rather than by continental drift 
(bottom). 




Rafting 




Island Stepping Stones 




Continental Drift 



69 




drift, would be dispersion of living 
creatures over isthmian links (like the 
Isthmus of Panama today), which in- 
cluded narrow land bridges between 
Africa and South America, for 
instance. 

On Continents, Ocean Basins 
and Icebergs 

The drift concept was first formal- 
ized by the Austrian meteorologist 
Alfred Wegener. He made rather bold, 
even bizarre, assumptions about the 
nature of continents and ocean basins 
such as were required by his hypothe- 
sis. Actually, most of his suppositions 
have turned out to be true. We have 
subsequently learned that continents 
are not deeply rooted masses of rock 
but instead are separated from the 
earth's mantle by a sharp boundary 
called the Mohorovicic Discontinuity, 
or the Moho. We also now know that the 
continental blocks around most of the 
Atlantic and Indian Oceans have "raw 
edges" — mountain ranges intersect the 
continental margin and abruptly stop. 
Since World War II we have learned 
that the ocean floor is crustless in the 
sense of having no liner of continental- 
type granitic rock or sial. And there is 
no question but that continents actual- 
ly float high because of their low den- 
sity. Continents all in all very much 
resemble icebergs. The plaguing ques- 
tion remains: Like icebergs, do they 
also drift? 

In our everyday experience, very 
large things are very hard to budge, 
so it defies our instincts that continents 
can be moved. But our instincts also 
deny other things — such as the entire 
earth moving around the sun sup- 
ported by nothing at all. Galileo was 



forced to recant this "illogical notion" 
before the Inquisition, but upon leav- 
ing is said to have muttered, "Eppur 
si muove" ( "But still it moves" ) . Late- 
ly the mechanical objection to drift has 
been removed by the suggestion that 
the earth's mantle undergoes a slow 
convection movement. In each convec- 
tion cell, the mantle material, rising as 
a semi-liquid current in the middle, 
curves outwards to the sides and de- 
scends along the edges. This is the 
simple, well-known convection move- 
ment of water when heated in a beaker. 
The mantle movement sluggishly flows 
merely a few centimeters per year. This 
would be ten million times slower than 
the flow within the earth's molten core 
whose liquid turbulence accounts for 
the magnetic field. If such convection 
does occur, the continents may be en- 
trained by the flow of the mantle and 
carried along as though on a conveyor 
belt. This would be fully analagous to 
the drift of icebergs which are trans- 
ported, not by any inherent or im- 
pressed force, but passively by the 
drift of the ocean. 

This mode of transport is independ- 
ent of scale. A huge iceberg is moved as 
readily as a bergy bit. In 1927 a 10,- 
000-square-mile iceberg, larger in area 
than the state of Rhode Island, drifted 
past the Faulkland Islands, off Argen- 
tina. So size per se is of no conse- 
quence. So far as the continents are 
concerned, we already know that sub- 
continental-size pieces drift. The 
northward motion of southern Califor- 
nia, relative to the remainder of North 
America, is a case in point. It brings 
Los Angeles two inches closer to San 
Francisco every year. 

Wegener erred in departing from 



70 



the iceberg analogy. He assumed that 
continents actively ploughed their way 
through the mantle like great ships at 
sea, using forces he called Westwand- 
erung (westward drift) and Poleflucht- 
krajt (pole fleeing force). These 
forces, although real, were shown to 
be negligibly small and served to dis- 
credit the continental drift concept for 
a few decades. 

A Jigsaw Puzzle 

The reconstruction of the ancient 
supercontinents envisioned by conti- 
nental drifters is a jigsaw puzzle. The 
jigsaw puzzle player has two clues: 
matching the picture, using color, tone 
or graphics; or fitting, using the shape 
of the pieces. The continental drift 
puzzle has the same clues. The "pic- 
ture" is sketched by the bedrock geolo- 



gy, the foldbelt trendlines, distribution 
of glacial formations (tillites), etc. But 
there are difficulties. The geological 
picture resembles an impressionistic 
painting. No two observers seem to 
agree whether or not any particular 
assembly is really pictorially in sharp 
focus. Also full rendering is hindered 
by the contiguous parts being sub- 
merged continental shelves which are 
zones of no picture information, or 
"white paper." Furthermore the prop- 
er pieces are the continental outlines 
as delineated by the 1000-fathom line 
rather than by the shoreline or the 
shelf edge. Our marine surveys are 
not sufficiently good as yet to delineate 
the position of this contour. 

Following Wegener's lead, many 
drifters have fitted the continents to- 
gether by forcing the fit, i.e., by taking 




The reconstruction of the ancient supercontinents envisioned by drifters is a 
jigsaw puzzle. 

71 




~^~- Tnassic fold belts 



□ Karroo 
Catarin 



and Santa 
o Systems 

Undifferentiated 



>k.(n^&^_ 




A jigsaw player has two clues. He may proceed by fitting the pieces by shape or 
by matching the design of the picture. Top: the pieces fit and the picture matches. 
Bottom: the pieces fit but the picture does not match. 

72 



great liberties with the shapes of the 
pieces as though the continents were 
made of rubber. The reconstructions 
of former supercontinents are easy to 
make by such sketch-map methods, 
but are they meaningful? Using conti- 
nental cutouts or templates for achiev- 
ing fit on a globe is another favorite 
device of drifters. Unfortunately some 
of these have been done on a globe of 
12-inch diameter or less. And one 
recent paper records the use of a 
6-inch globe! Good "fits" are easy to 
achieve on a ping-pong-ball-sized 
globe. 

Nonetheless, the case for the former 
existence of the southern hemisphere 
supercontinent of Gondwana, at least, 
is particularly strong. Attempting its 



reconstruction is a fascinating jigsaw 
puzzle — a game for the Gods, as some 
of the pieces are missing. 

Tibetan Plateau: Two Continents Thick 

India is universally recognized by 
drifters as a part of Gondwana, al- 
though it is physically attached to Asia. 
Geologists agree that the rocks of India 
are wholly unlike those of Asia. India's 
present position is ascribed to its hav- 
ing impinged against the underbelly of 
Asia on its journey north, forcing up 
the Himalaya Mountains and the Ti- 
betan Plateau in the process. This may 
seem too much to believe, but it is ac- 
tually reasonable. Tibet is 14,000 feet 
high, or equivalent to the relief of a 
continental slope. Looking north at 



issoe ? 




Following Wegener's lead, many drifters have made forced reconstruction by 
considering the continents as pliable as rubber . . . but are such fits meaningful? 



73 




Good fits are easy to achieve on a ping-pong-ball-sized globe. 



the Himalayan rampart from the resort 
city of Darjeeling, one sees the only 
land scarp in the world as grand as the 
continental slopes which surround all 
continents. The reason is precisely the 
same — -the Indian continental plate 
has underridden the Asian plate, pro- 
ducing a double continent 70 km thick. 
Since continents float isostatically (i.e., 
are floating hydrostatically), the Ti- 
betan Plateau is two continents high 
relative to the deep-ocean floor and 
one continent high relative to the land 
surface of India. 

Almost Perfect Fit 

Of course, the fitting of South 
America into Africa is a straightfor- 
ward proposition. The parallelism of 



these opposing shorelines across the 
South Atlantic has been an inspiration 
to all drifters since the time of Wege- 
ner. He claimed that the geologic rec- 
ord could be read between South 
America and Africa as well as if those 
continents were pieces of a torn sheet 
of newspaper — a bit of an overstate- 
ment. The sketch maps of drift invari- 
ably show this fit but it apparently 
was thought to be only approximate. 
Only recently have geologists made the 
transposition with cartographic pre- 
cision and, surprisingly, discovered that 
it dovetails beyond even the fondest 
hopes of the drift enthusiasts. Not only 
does the bulge of South America fit 
into the bight of Africa but the major 
bumps fit as well, and to some extent 



74 



so do the bumps on the bumps. Some 
overlaps and gaps remain, but consid- 
ering the vicissitudes of geologic his- 
tory, the fit is too remarkable to be 
fortuitous. It must mean that these two 
continents were once juxtaposed. Our 
maps show a great ocean between Af- 
rica and South America, but geologi- 
cally these two continents should be 
contiguous and conterminous. 

Walter Sproll and I have recently 
obtained two other rather good Gond- 
wana fits using precise and computer- 
ized methods. One of these places 



India, including Ceylon, against west- 
ern Australia. Another wraps the south 
coast of Australia around Antarctica 
from the region of the Ross Sea west- 
ward. Many problems remain, how- 
ever, before entire Gondwana can be 
pieced together using strict morpho- 
logic criteria. And we must stick to 
the rules, too, for the continental jig- 
saw game is not without constraints. 
It is not cricket, for example, to play 
continental leapfrog, although one 
South African geologist alleges that 
some jump-fits are as good as any of 



Continental drift is a game for the Gods as some of the pieces are still missing. 




75 




India's present position is ascribed to its having impinged against the underbelly 
of Asia on its journey north, forcing up the Himalaya Mountains in the process. 



those usually promoted by drifters. 

The Mesozoic Break-Up 

My tentative speculation as to how 
the continents dispersed would begin 
with the breakup and dispersal of the 
two supercontinents Laurasia and 
Gondwana commencing late in the 
Jurassic Period, in the middle of the 
age of dinosaurs, about 150 million 
years ago. Most likely this was a unique 
event in earth history. Certainly the 
continents have not been repeatedly 
fragmented through geologic time. 
There clearly had been a long period 
of geologic calm before this abrupt 
dispersal. In the northern hemisphere, 



North America swung away from Eur- 
asia, rotating on a hinge point in south- 
eastern Alaska. Previously Canada had 
been tied to Europe, and the eastern 
United States faced an Atlantic Ocean 
differently configured than now. 

The southern continents were prob- 
ably clustered together to form Gond- 
wana and centered in the mid-Indian 
Ocean. An X-shaped rift opened up 
which dispersed India, South America- 
Africa, Antarctica, and Australia to 
the four directions of the compass. 
Sometime later, South America split 
off from Africa and moved still farther 
westward. The main stage of this scat- 
tering of crustal pieces was largely 



76 




Alfred Wegener claimed that the geologic record could be read between South 
America and Africa as well as if they were pieces of a torn sheet of newspaper — a 
bit of an overstatement. 



11 




78 




Our maps show a great ocean between Africa and South America but because of 
geological features and similarities these two continents should be contiguous and 
conterminous. 



79 







s& 






The continental drift jigsaw game is not without constraints. It is not cricket, for 
example, to play continental leapfrog, although one South African geologist claims 
that some jump fits are as good as any of those usually promoted by drifters. 



over by the end of the Mesozoic Era, 
60 million years ago. 

Drift was initiated by the earth's 
mantle becoming suddenly "restless" 
and undergoing some sort of overturn 
in response to having built up too much 
internal heat by the slow decay of 



radioactive uranium, thorium and po- 
tassium. The great world-wide sinu- 
ous mid-ocean ridge with its central 
rift was the scar resulting from this. 
But this seems only approximately 
true ; for the continents cannot be fitted 
back into this linear birth scar. The 



80 



mid-ocean rift virtually encircles 
Africa (except in the Mediterranean) 
forming a "ghost of Africa," an en- 
larged outline of the continent, which 
apparently expanded outward in all 
directions. 

The effect of continental breakup 
can thus be seen around Africa, for it 
was the heartland of Gondwana. In 
pre-drift time, only the north coast of 
Africa now facing the Mediterranean 
was open to the world ocean. The rift- 
ing presumably began along the north- 
east coastline of India, detaching India 
and then Madagascar. The splitting 
then extended southward, along Mo- 
zambique to Cape Horn, detaching 
Antartica. Next the rifting turned 
northward up the Atlantic side of 



Africa, separating South America. 
Thus nearly all of the coastline of 
Africa was blocked out and a modern 
shoreline established 150-100 million 
years ago (in late-Jurassic to mid- 
Cretaceous time), the heroic period of 
continental drift. 

The post-Mesozoic period of qui- 
escence was temporary, ending about 
15 million years ago. It now appears 
that the unstable ends of the snake- 
like mid-ocean rift have shifted. One 
tail, formerly in the central Pacific, 
has swung under western North Amer- 
ica opening up the Gulf of California 
and arching the entire western limb of 
our continent. Another tail, in the 
Indian Ocean, has circled into the Red 
Sea and down through eastern Africa, 



In Australia, the belief is popular that the continents have been dispersed by an 
expanding earth. 




creating the African Rift Valleys. The 
Arabian block has recently been trans- 
lated 200 km and rotated counter- 
clockwise 8°. 

A Final Comment 

In Australia the belief in an expand- 
ing earth is a popular explanation for 
the apparent continental dispersion. It 
is proposed that the ocean basins alone 
have essentially doubled their surface 
area in the past 1 50 million years while 
the continents have remained un- 
changed in size and shape. I can hardly 
accept this interpretation, for such an 
expansion would have resulted in a 
great lowering of sea level. A funda- 
mental relationship exists between the 
depth of the sea and the thickness of 
the continental plate so that any draw- 
down of sea level would have caused 



catastrophic denudation of the conti- 
nental areas. The resulting erosional 
havoc to the continents would be clear- 
ly visible in the geologic record, but it 
is not. The continents would have been 
stripped of their Paleozoic veneers of 
marine sediments, but they have not. 
Although controversy continues un- 
abated, the theory of continental drift 
bolstered by the new evidence of pale- 
omagnetism, after a period of rejec- 
tion, is now very much alive. Project 
Mohole is dead, but a new program 
jointly sponsored by a consortium of 
oceanographic institutions for drilling 
many shallow holes in the deep sea 
is now in the offing. When the results 
of this effort are finally assessed, I am 
quite sure that we will find that our 
shifty continents are, and have been, 
on the move. 



82 



14 



Reprinted from AMERICAN JOURNAL OF SCIENCE Vol. 265 
[Amfrican Journal of Scikncf., Vol. 265, March 1967, P. 231-237] 

PASSIVE CONTINENTS, SPREADING SEA FLOORS 
AND CONTINENTAL RISES: A REPLY 

ROBERT S. DIETZ 

Environmental Science Services Administration, 

Institute for Oceanography, 

Silver Spring, Maryland 20910 

This reply pertains to a discussion in this journal, by Grant M. 
Young, of. my paper "Passive continents, spreading sea doors, and con- 
tinental rises" (Dietz, 1966) and earlier publications (Dietz, 1963a; Dietz 
and Holden, 1966a). It is a pleasure to attempt to bring into sharper 
focus our differing viewpoints. I would like to thank Walter Sproll and 
Rose Hudson for assistance in preparing this manuscript. 

Multiple orogenies— -There are, of course, many examples of a 
single region being affected by a later orogeny; Young cites a few for 
Canada. I don't think this adds much to the argument as to whether 
foldbelts have been repeatedly tectonized or not. I doubt, however, his 
Belcher Island orogeny. Future studies probably will show that this 
foldbelt is related to the Hudson Bay (Nastapoka Arc) astrobleme, an 
impact scar imposed on the craton and not a true otogenic foldbelt 
(Beals, Innes, and Roltenberg, 1963). I argued for more tectonic stabil- 
ity in Earth history than is found, for example, in the textbook view- 
point that: "We find in the geologic record of all .continents evidence of 
ancient movements on a gigantic scale, which repeatedly changed the 
geography of the globe. The bedrock has been fractured, bent, or 
mashed, and in general the oldest rocks give the most eloquent testi- 
mony of crustal unrest, because they have been subject to deformation 
repeatedly during geologic time" (Longwell, Knopf, and Flint, 1939, p. 
313). This belief in such high otogenic mobility has been modified in 
their later editions. Certainly the great antiquity of many little deformed 
and metamorphosed sedimentary strata, formerly regarded as Eo-Cam- 
brian, argues for more cratonic stability than previously recognized. The 
great calm of geologic history is equally as impressive, if not so dramatic, 
as the orogenies. 

Certainly the Precambrian age of many little-deformed and well- 
preserved sedimentary sequences is one of the surprises of modern 
geology. We may cite, as Canadian examples, the probably Precambrian 
Athabaska formation regarded as between 1400 and 1800 million years 
and especially the remarkably similar Dubawnt group regarded as about 
1500 million years (Fahrig, 1961). This all seems to be most understand- 
able if eugeosynclinal Archean-type beds become tectonized by virtue of 
their geologic position mostly as collapsed continental rise prisms. The 
Ep-Archean unconformity then is "profound" only because ensialic plat- 
form beds laid down on the craton tend not to become tectonized. 

231 



232 Reply 

My principal disagreement with Stockwell's (1964) interpretation 
of the Grenville foldbelt is that I doubt'that a preexisting continental 
strip was orogenized. Sialic material, yes, for a continental rise is com- 
posed of sialic detritus, and juvenile magmas would also be sialic by my 
concept. Regarding the number of orogenies involved, I presume that 
there may have been several, but these probably were pulses in the one 
grand Grenville orogeny sensu lato—as with the Appalachian orogeny 
which, in the broad sense, occupied the entire mid- and late-Paleozoic. 
It seems to me that the abrupt transition across the Grenville Front is 
most readily accounted for by a continental rise. 

Young cites some Canadian opinion favoring multiple orogenies. 
On the other hand, Wilson (1949) states that he "knows of no evidence 
which proves that any large area of the Canadian Shield has been sub- 
ject to two periods of folding and mountain building differing widely 
in time". Without doubt the final word on this subject remains to be 
spoken. 

Sialic or simatic basements to eugeosynclines?.— Young quotes Dott 
(1964) to the effect that simatic basements are wholly unknown beneath 
eugeosynclines. It should be pointed out, in the first place, that geologists 
tend to restrict the term basement to granitoid rocks and so by definition 
rule out any simatic rock found as qualifying as basement. And we can 
probably generalize Dott's statement to say that no basements under 
eugeosynclines are known with certainty. For example, the basement 
of the crystalline Appalachian orogen is unknown; but we may argue, 
with some logic, that if it were sialic it should appear, as granitoid rocks 
are low density masses. Simatic rocks, on the other hand, are heavy and 
would tend not to rise. It is also not clear what Dott would admit as 
oceanic rocks. For my part, spilites, serpentinites, and ultramafics (most- 
ly peridotite) all qualify (Dietz, 1963b). These do occur in eugeosyn- 
clines and, I suppose, constitute fragmented and tectonically incorporated 
pieces of the basement. By my geosynclinal concept, one would expect 
such tectonic incorporation of simatic rocks rather than any continuous 
basement (as with the sialic basement under a miogeosyncline) because 
the foldbelt is as thick as the continental plate. 

Young refers to the Grenville as Proterozoic rocks laid down on a 
continental plate that was not passive; but my point was that such highly 
orogenized rock could not have been laid down on any continent at all 
but rather ensimatically. Some confusion is introduced as Young follows 
the new Precambrian classification of Stockwell (1964) which introduces 
a new tongue-twisting Greek-root terminology. It is pertinent here to 
note that such new subdivisions of the Precambrian based on radio- 
metric dating differ markedly from the classical classification based 
largely upon degree of deformation and metamorphism. Although now 
considered Proterozoic, the Grenville rocks are of the Archean litho- 
facies in the classical sense. We can understand such basement complexes 



Reply 233 

as being of any age if they are collapsed and intruded continental rises 
deformed by virtue of their ensimatic position. Such prisms must be 
deformed in order to be thickened vviiich then provides the bouyancy 
needed to achieve a subaerial position. To achieve continental accre- 
tion, rock thicknesses of about 20 miles must be attained; collapsing con- 
tinental rises uniquely offer a simple orogenic theory capable of doing 
this. 

Young asks why the fact that orogenic zones are clean-cut (for 
example, llie contact between the crystalline Appalachians and the 
folded Appalachians), rather than vaguely merging, favors the collapsing 
continental rise interpretation of eugeosynclines. The other principal 
orogenic theories are the tectogene and the tectonic-borderland/island- 
arc concepts. Both of these involve the orogenizing of a previously exist- 
ing continental sialic plate. Such a plate is a uniform realm so it is not 
clear why a tcctonized foldbelt should cease abruptly. On the other hand, 
by the collapsing continental rise concept, the line between an accre- 
tionary orogen and the older craton is the continental margin (the con- 
tinental slope) , a realm of abrupt topographic, geologic, and petrologic 
contrast. The Grenville Front may be a zone of some faulting, especially 
thrusting. Stockwell's (1965) tectonic map of Canada shows about one- 
third of the front to be a fault contact, but more fundamentally I sup- 
pose that it may be the trace of a former continental slope. 

Young cites some evidence that the Sudbury lopolith could not have 
been emplaced near the pre-Grenville continental margin contra my 
belief that its deformation (a squashing from circular to oval) may only 
provide evidence for deformation in proximity to a continental margin 
rather than cratonic interior orogenesis. May I suggest that the wedge 
of Huronian sediments thickening toward the Grenville Front around 
this region may provide a Precambrian example of a continental-margin 
terrace wedge or miogeosyncline (Dietz and Holden, 1966b). In their classic 
paper on the Dissappearance of the Huronian, Quirke and Collins (1930) 
were faced with the problem of a sedimentary wedge which became ever 
thicker and then abruptly terminated at what is now called the Gren- 
ville Front. They "solved" this problem by presuming granitization of 
sediment on a vast scale within the Grenville zone. It is not necessary, 
however, to presume that a sedimentary wedge that thickens must again 
pinch out, implying that all thick sedimentary deposits are laid down in 
basins. Continental terrace wedges laid down on a continental shelf 
characteristically thicken out if modern examples are taken as diagnostic 
(Dietz and Holden, 1966b). Accordingly, the disappearance of the Huron- 
ian sediments may be an entirely normal termination by thickening out 
at the pre-Grenville continental margin. 

Accretion of North America— It is better to consider the case for 
accretion in reference to the younger crystalline Appalachian orogen 
than to the Grenville. To disprove accretion, Young shows some outliers 



234 Reply 

of Precambrian near the continental nfargin in his figure 1; and they 
are also referred to by Gastil (1960) . Three examples exist in the north- 
ern Appalachian belt— in Massachusetts, Nova Scotia, and Newfoundland. 
But these are all in the age range from 500 to 800 million years, and so 
are Cambrian to Eo-Cambrian, and thus are not outliers of the Gren- 
ville rock dated as around 1000 million years (P. King, personal com- 
munication; tectonic map of North America, in preparation). Thus their 
inclusion in the Appalachian bell is consonant with accretion and sug- 
gests only that some Appalachian thermal events date into the late Pre- 
cambrian. 

An alternate suggestion is Wilson's (1966) who regards them as 
fragments of Europe and Africa left after the lower Paleozoic impinge- 
ment and subsequent separation of Eur-Africa. I personally am not in- 
clined to accept this speculation, but it is an example of the type of 
transformation that may be needed before the problem of accretion 
is finally worked out. 

The existence of the Baltimore gneiss within the crystalline Ap- 
palachians is not so readily explained, as these are rocks of Grenville age. 
The term gneiss suggests sialic basement, but Hopson (1964) considers 
that this gneiss most likely has been metamorphosed from volcanic rocks 
similar to the Eocene-Oligocene spillitic suit of the Pacific Northwest. 
This suggests that they are the metamorphosed equivalents of oceanic 
rocks (layer 2) rather than continental sialic basement. 

The San Gabriel norite-anorthosite complex of California is cited 
by Young as evidence for no accretion to North America. I have com- 
mented upon this elsewhere (Dietz, 1965) noting other possible ways to 
account, from the accretionary viewpoint, for this anomalous outlier of 
ancient rock. One may wonder, in the first place, if this largely mafic 
mass qualifies as a true cratonic block; it may be an entrapped sea floor 
fragment. Silver and others (1963) emphasize its anomalous nature by 
stating: "These age determinations provide the first compelling evidence 
of Precambrian rocks on the west coast of North America". The San 
Gabriel mass is probably an allocthonous block rather than an outcrop 
of a Precambrian terrane underlying the California coast. 

Accretion and continental drift.— Stockwell's tectonic map of Canada 
does, in my opinion, support continental accretion if we look for what is 
usual rather than anomalous. Considering the vicissitudes of geologic 
history, we cannot, of course, expect accreted continents to have a perfect 
onion-like structure— only to be more onionlike than layer cake-like 
(Dietz, 1966). Furthermore, accretion and continental drift (rifting and 
drifting apart) are complementary processes under my sea-lloor spreading 
concept, so that we cannot expect the final accretionary pattern to appear 
until we solve the drift problem. 

Fitch's (1965) chelozonic map for showing the structural unity of 
North America and Europe by radiometric age zonation strikes me as 



Reply 235 

reasonably consistent with continental accretion by collapsing contin- 
ental vises if Ave exclude the bulge of Africa as ever being against the 
United Slates. The main discrepancy lies in the north-trending Varisco- 
Caledonian gcosyncline extending through Norway and marginal to 
Greenland. If Laurasia still existed in the Paleozoic, as seems likely, this 
would have to lip ronslrnod to be an inn acralonic but not necessarily 
ensialic geosynclinc. 

The foldhelts off western North America are concordant as should 
cluirai lei i/c ace rolionaiy bells. Oil eastern Canada llic fold bell appears 
to become discordant, striking toward the deep sea. Here the continental 
slopes are probably modified rift scars remaining from the break-up of 
Laurasia in (he Mcsozoic. Regarding the continental-drift fit of con- 
tinents around the Atlantic Ocean, Walter Sproll and I (ms) have 
studied the continental drift jigsaw problem using precise cartographic 
methods and a computer program. Our present view is that the bulge 
of Africa juxtaposition of the United States is really a misfit; some others 
seem valid. Thus we prefer the Laurasia-Gondwana option for the drift 
reconstruction of continents. Accordingly the Appalachian foldbelt 
would have formed marginal to a continent and not intracratonically. 
An alternate suggestion by Wilson, which also is consistent with the 
Appalachian geosyncline being extra-cratonic, has already been noted 
above. 

Universal sialic crust and intracratonic geosynclines?.— r To avoid 
totally the continent-edge problem, one must assume a universal sialic 
crust in Precambrian time. Creer (1965), for example, has supposedly 
demonstrated a remarkable fit of the present continents on a globe of a 
radius approximately 0.55 times that of the present Earth, so that the 
continents once would have formed a continuous "skin" around the 
Earth. With universal sial, we would have no ocean basins and all the 
continents would have been covered to a depth of 2440 meters even for 
an Earth of the present diameter— an absurdity. To believe that nearly 
all the hydrosphere is of recent generation is equally untenable 

The small scale and distorted projection used by Creer make it im- 
possible for the reader to evaluate his universal fit. But how poor the 
fit must be is indicated by Creer's initial assumption that the contin- 
ents occupy only 30 percent of the present Earth. While the Earth's sur- 
face is 29 percent land, it is correct to include also as continents the 
continental shelves and the slopes down to the 1000-fathom isobath. 
The Earth is covered by 40 percent continental crust and 60 percent 
oceanic crust down to the 1000-meter isobath (Hess, 1962). Menard (1964, 
p. 235) gives the area of continental crust as 2.1 x 10 8 km 2 and the area of 
oceanic crust as 3.0 x 10 8 km 2 , or 41 percent continental crust. This alone 
means that on an Earth with a radius of only 55 percent that of the mod- 
ern Earth, the sialic skin would have a one-third overlap. So how can we 
accept Creer's fit? 



236 Reply 

Young prefers to believe that all geosynclines are intracratonic. 
Some geosynclines are, of course, intracratonic, but my view is, briefly, 
that those that consist of the mio-eugeosyncline couplet are formed mar- 
ginal to continents with the former being ensialic and the latter ensima- 
tic as evidenced by entrapped presumed sea-floor rocks (spilites, serpen- 
tines, and peridotites). Some intracratonic geosynclines were nevertheless 
ensimatic, for example the Ural geosyncline as evidenced by its ser- 
pentine belt (Dietz, 1963b). Delving further into this discussion would 
be beyond the scope of this reply. 

Young suggests that the present positioning of deep oceans over 
simatic crust is atypical of geologic history. But, for reasons of isostasy, 
the division of the world into sialic and simatic realms is necessary for 
the very existence of ocean basins. And these are clearly needed to con- 
fine the 1350 x 10° km 3 of seawater present on Earth, a volume which 
cannot have grown appreciably since Precambrian time. 

To fragment an initial universal sialic crust is another way out, but 
I cannot take the expanding Earth hypothesis of Egyed (1961) and others 
seriously. Egyed supposed that the Earth had an original density of 35 
and enlarged at a rate of 7 millimeters per annum. His sole geologic 
argument concerns the withdrawal of water from the continents during 
the Phanerozoic, using the paleogeographic maps of the Termiers and of 
Strakov. For several reasons this evidence is specious, for example: (1) 
Egyed considers the continents to be now 100 percent emergent but they 
are only about 88 percent if we include the continental shelves to the 
shelf-break found usually at about 65 fathoms. Also not taken into con- 
sideration is the atypical withdrawal of water due to glacial ice. The 
return of this water to the ocean would cause North America to be about 
25 percent submerged. (2) The extent of transgression and regression of 
shallow platform seas across the continents is largely a measure of the de- 
gree of ultrapeneplanation and nothing else. (3) It is generally recog- 
nized that continents have maintained high relief during the Geno/oic 
for tectonic reasons and not because the deep ocean has become shal- 
lower. (4) If continents actually have gained "freeboard" since the Pre- 
cambrian, they should be largely stripped of their extensive Paleozoic 
cover, but they have not been. 

Concluding remarks.— I, of course, do adhere to actualism and uni- 
formitarianism, but is this "unwarranted"? It seems to me that the 
burden of proof falls upon those who would downgrade this principle 
of geology by arguing, for example, that there are no modern examples 
of the ancient orthogeosynclines or, conversely, that the modern para- 
liageogynclines (like the Atlantic and Gulf modern accumulations) 
belong to an entirely new species. If so, where are the ancient continental 
terrace deposits and the continental-rise prisms? The usual ensialic 
geosynclinal theories ignore the basic dichotomy of the Earth into sialic 
and simatic segments, and the presence of the continental slope (the great 
scarp connecting these two realms) is ignored. 



Reply 237 

References 

Beds. C. S., Inncs, M. J. S., and Rottenbcrg, J. A., 1003, Fossil meteorite craters, in 

Middlchursi, B. M., and Knipcr, G. P., The Solar System, v. 1: Chicago, Illinois, 

Univ. Chicago Press, p. 235-281. 
Crccr, K. M., 1905, An expanding cartli?: Nature, v. 20"), p. 539-544. 
Diet/, R. S., 1903a, Collapsing continental rises: An actualist ic concept of geosynclines 

and mountain building: Jour. Geology, v. 71, p. 311-333. 
, 11)631), Alpine serpentines as oceanic rind fragments: Gcol. Soc. America 

Bull., v. 74, p. 917-952. 

-, 1905, Collapsing continental rises: an actualisiic concept of geosynclines 



and mountain building: a reply: Jour. Geology, v. 73, p. 901-906. 

1900, Passive continents, spreading sea floors and collapsing continental 



rises: Am. Jour. Sci., v. 204. p. 177-193. 
Dictz, R. S., and Holder), J. C, 1900a, Deep sea deposits in but not on the continents: 

Am. Assoc. Petroleum Geologists Bull., v. 50, p. 351-302. 
1900b, Miogcoclines (miogeosynclines) in space and time: Jour. Geology, 

v. 7-1. p. 566-583. 
Dictz, R. S., and Sproll, W, P., 1960, Marine geologic aspects of continental drift and 

Gondwana [abs.]: Intcrnat. Occanog. Cong., 2nd, Moscow 1906, p. 97-98. 
Dott. R. II., Jr., 1901, Mobile belts, sedimentation and orogenesis: New York Acad. 

Sii. Trans., sci. 2, v. 27, p. 135-114. 
Egvcd. I,.. 1901, The expanding earth: New York Acad. Sci. Trans., ser. 2, v. 23. 

' p. 424-132. 
Fahrig, \V. F., 1901. The gcologv of the Athabaska formation: Canada Geol. Survey 

Bull., v. OS, 41 [). 

Fitch. F. J., 1965, The structural unity of the reconsiructed North Atlantic continent: 

Royal Soc. [London] Philos. Trans., v. 258, p. 191-194. 
Gastil, R. G, 1900, The distribution of mineral dates in time and space: Am. Jour. 

Sci., v. 258. p. 1-35. 
Hess. II. II., 1902, History of ocean basins, in F.ngel, A. F. J.. James, H. L., and 

Leonard, B. F. eds. Pctrologic Studies: a volume in honor of A. F. Buddington: 

New York, Gcol. Soc. America, p. 599-020. 
Hopson, C. A., 1964, The crystalline rocks of Howard and Montgomery Counties 

[Maryland], in I lie geology of Howard and Montgomery Counties: Baltimore, 

M. inland, Mankind Gcol. Survey, p. 27-215. 
Longwcll, C. R.. Knopf, Adolph, and Flint, R. F., 1939, A tcxtlwok of geology: New 

York, John Wiley & Sons, Inc., 543 p. 
Menard, H. W., 1901. Marine geology of the Pacific: McGraw-Hill Hook Co., New York, 

271 p. 
Quirke, T. T., and Collins, W. H., 1930, The disappearance of the Huronian: Canada 

Gcol. Survey M< m. 100, 129 p. 
Silver, L. T., "M< Kinney, C. R., Dcutsch, S., and Bolinger, J., 1903, Prccambrian age 

determinations in the western San Gabriel Mountains, California: Jour. Gcologv, 

v. 71, p. 190-214. 
Siockwell, C. II., 1901, Age determinations and geological studies: Canada Geol. 

Survey, Dcpt. Mines Tech. Surveys Paper 64-117, pt. 2, 30 p. 
■ . 1905, Tectonic map of the Canadian Shield: Canada Gcol. Survey, Dcpt. 

Mines Tech. Surveys, Map 4-1965. 
Wilson, J. T., 1949, Some major structures of the Canadian Shield: Canadian Inst. 

Mining Metallurgy Trans., v. 52, p. 231-242. 
, 1966, Did the Atlantic close and then re-open?: Nature, v. 211, p. 676-681. 



15 



Shatter Cone Orientation at Gosses Bluff Astrobleme 



by 
ROBERT S. 



DIETZ 



Institute for Oceanography, ESSA, 
Miami, Florida 



Shatter cones caused by shock fracturing are widely developed at the 
Gosses Bluff cryptoexplosion ring structure in central Australia. The 
force field can be reconstructed whereby the applied shock arrived 
centrally and from above, which is consistent with a cosmic impact. 
For this and other reasons, Gosses Bluff is an astrobleme. 



Gosses Bluff is an isolated, ring structure of upturned 
Lower Palaeozoic rock nearly 3 miles across, situated 
in the Amadeus Basin of central Australia, about 200 km 
west of Alice Springs. It rises about 700 ft. above the 
surrounding plain and is breached by an intermittent 
stream, on the north-east side. The term "bluff" is 
something of a misnomer, or at least is an inadequate 
description. 

The interior bowl shaped basin might well be misinter- 
preted as a modern meteorite crater (Fig. 1). It is, how- 
ever, at the same level of erosion as the surrounding plain 
and is not depressed, and there are no remnants of lake 
beds which would indicate that a former closed basin exis- 
ted here. Furthermore, geological inspection shows that it 
is the upturned ring of a great dome, the soft centre (Lara- 
pinta) of which has been erosionally gutted, forming the 
central bowl. Lining the bowl, the cliff-forming Meerenie 
sandstone now stands etched out in high bold relief and is 
in turn surrounded by the Pertnjara formation. 

If Gosses Bluff is to be interpreted asametoorite structure, 
then it can only be regarded as an astrobleme — an ancient 
cosmic impact scar, with the bluff per se being the uplifted 
central dome of a much larger circular structure. Although 
the strata are largely hidden from view outside the bluff, 
this interpretation is quite permissible. Gravity and 
magnetic surveys at the Bureau of Mineral Resources 
show that the bluff marks the centre of a circular deforma- 
tion 12 miles wide. A structure of this size is also apparent 



as a double "ghost ring" on a Gemini IV photograph 
from near space (Fig. 2). 

On the basis of much evidence of explosive force, Crook 
and Cook 1 rejected an earlier view which was widely held, 
that Gosses Bluff was a salt diapir: while agreeing that it 
was of cryptoexplosive origin, Crook regarded it as an 
astrobleme and Cook thought it was crypto volcanic. 







Fig. 1. Aerial oblique view of Gosses Bluff lookin" south, showing the 
ring of upturned strata. 



NATURE. VOL. 216. DECEMBER 16. 1967 



1083 




with the possible exception of the Vredefort Ring of South 
Africa. The coning is least developed in the southern 
quadrant and most strongly developed in the northern 
quadrant where, in places, nearly all rock talus revealed 
shatter coned faces. There is also a strongly preferred 
orientation of the cone apexes. In the vertically dipping 
Larapinta formation of the central basin and in the 
Meerenie sandstone marking the interior "lining'' of the 
uplifted ring, tho shatter cones are oriented radially 
outward — that is, normal and upward with respect to 
bedding. Further out from ground zero (4,000-7,000 ft.) 
in the Pertnjara formation, the shatter cones point 
generally outward but only at angles of about 60° upward 
with respect to bedding. Still further out, at two sites, 
shatter coning is oriented upward and parallel to bedding. 
The first of these two sites occurs close to the spot where 
the road track enters the breach in the bluff ring at a 
position about 10,000 ft. north-east of ground zero. The 
other site is a hogback, fully detached from the ring 
proper and lying about 13,000 ft. north-west of ground 



Fig. 2. Gemini photo of Gosses Bluff from near space. Dark circle in 

centre marks the upturned ring of rocks 2-5 miles across. Note "ghost 

ring" surrounding Gosses Bluff which identifies the full extent of the 

structure, 12 miles across. 



Cook 2 has since revised his opinion and concurs in the 
astrobleme interpretation. Daniel Milton and Robin 
Brett, who are at present mapping this structure in 
detail as a joint project of the US Geological Survey 
and Australian Bureau of Mineral Resources, also regard 
it as an astrobleme. Their results will soon be published. 
This article is limited to a discussion of shatter coning at 
Gosses Bluff which further supports this interpretation. 

Shatter cones (Fig. 3) wore first noted by Crook and 
Cook, who, however, regarded them merely as an inciden- 
tal aspect of the structure with the orientation of the 
shatter cone being random. Actually, Gosses Bluff is 
the most intensely shatter coned of the eighteen sites I 
know around the world 4 and the cones show a high degree 
of preferred orientation which reveals the shock force 
field impressed on the structure. Crook and Cook also 
doubted the validity of shatter cones as a criterion for 
astroblemes, but I have attempted to answer their objec- 
tions elsewhere 5 . 

In order to study the shatter cone orientation and 
distribution at Gosses Bluff, I made several spoke-like 
traverses of the structure commencing at the centre 
(ground zero) and working radially outward. Shatter 
coning was found to be extensively developed throughout 
the structure on a scale which I have never before observed. 




(TH mm m Tin in iiri'l IM tn Htxk 



K ^< 






^F 



~t— --' 



V 



__™ m /5i'V% K /'^0v>^_^^, T ^/^\/7 7\_ 






/ * A / ! v v A 

/ P/ / - M 7 / L \ \ M; \ 


s P 





MILES 




Fig. 3. A group of shatter cones from the Pertnjara formation showing 
orientation oblique to bedding. 



Fig. 4. Diagrammatic representation of shatter cone orientations at 
Gosses Bluff revealing the shock wave force Held which was impressed 
on the structure. A, Impact of bolide and radial spreading of shock 
wave instantaneously prior to upheaval. L, Larapinta group; M, 
Meerenie sandstone; P, Pertnjara formation. B, Presently observed 
orientation of shatter cones (arrows) in upturned strata. Vertical 
exaggeration. 2:1. 



If one can envision a return of the rocks to their 
presumed pre-event, essentially horizontal position, wo 
observe a pattern of shatter coning which reconstructs 
the shock wave force field which acted on the structure 
(Fig. 4). Before upheaval the shatter cones in the central 
region pointed directly skyward, those farther out pointed 
inward and upward, while those farthest out pointed 
radially inward. Because the apices of shatter cones 
point toward the impressed shock wave front, this indi- 
cates a shock originating from above as, most likely, 
the impact of a cosmic body with an apparent or 
effective diameter (that is, for purpose of impressing a 
parallel shock front) of about 7,000 ft. This derived 
diameter may well be beyond the limits of resolution of the 



1084 



NATURE. VOL. 216, DECEMBER 16, 1967 



method and the object could have been much smaller 
because we are now examining an inverted mass of rock. 
The strata now at ground zero were originally positioned 
several thousands of feet deeper. This effect tends to 
enhance the normal and upward-to-bedding aspect of 
shatter cones. Nevertheless, the apparent diameter 
of the bolide would seem to have been at least a few 
thousand feet. 

As elsewhere, thero are exceptions to the preferred 
orientation noted here, but those are sufficiently few to be 
regarded as uncommon. Most often, fully inverted cone 
orientations are found ; more rarely the cones point 
randomly. It is necessary, of course, to distinguish 
positive cone faces from negative ones and to measure the 
apical direction of a full 360° cone rather than the direc- 
tions of various cone segments ; otherwise confusion 
results, giving a false appearance of randomness. According 
to the impact interpretation, random and inverted orienta- 
tions may be ascribed to the reflexion of shock waves 
which were still sufficiently intense to cause shatter 
coning. 

Outcrops in the outer annulus of the structure, and 
peripheral to Gosses Bluff proper, are few and far between. 
Those outcrops which were found were searched; no 
shatter cones were found. Possibly at this range of from 
2 to 6 miles from ground zero, shock pressure had already 
dropped below the level required to produce shatter 
coning (20 to 80 kbars). It would not be surprising, how- 
ever, if a further search revealed some shatter coning 
on a reduced scale. This places Gosses Bluff in an inter- 
mediate position among known shatter coned structures, 
in most of which shatter coning is confined to the central 
eye (for example, Serpent Mound, Ohio) and the very 
large astroblemes where shatter coning extends outwara, 
15 miles or more (Sudbury, Vredefort Ring). 

At seven sites around the bluff, I found nests of breccia 
containing shatter coned fragments. In no case does the 
shatter coning extend into the breccia matrix. This is 
expected for an astrobleme because, in a cosmic impact. 
the target is first engulfed by the shock wave, followed 



almost instantaneously, but clearly separated in time, by 
brecciation and upheaval. 

The bluff is circular in its external limits : the interior 
plan, however, as outlined by the Larapinta and Meerenie 
formation, has the form of an equilateral triangle with 
truncated basal angles and with a sharp apical angle to 
the north, giving the internal structure an overall penta- 
gonal form. An imaginary line running from north to 
south through the apex provides an axis of bilateral 
symmetry. Such bilateral symmetry is a well known 
aspect of some other astroblemes 3 and it could reflect 
the arrival of the bolide at an oblique angle from the 
south and towards the north. Shatter coning is clearly 
more intensely developed at the northern apex of the 
structure than elsewhere. 

While I remain convinced of the astrobleme interpreta- 
tion, numerous questions remain unanswered. First, 
what was the original form of the crater ? Second, why 
is tho central dome so large (about 3 miles) and uplift 
so great (about 10,000 ft.) with respect to the overall 
12 mile diameter of the structure ? One suggestion is 
that the cosmic bolide was a comet head combining 
sufficient excessive hypervelocity and low density to pro- 
vide for a surface or very shallow detonation which 
enhances tho central uplift effect 6 . Third, what is the 
age of the structure ? As Crook and Cook point out, 
Gosses Bluff appears to have been exhumed after early 
Tertiary peneplanation so that a Mesozoic age seems 
reasonable. 

I thank Milton, Brett and George Berryman for 
hospitality and the Bureau of Mineral Resources of 
Australia for logistical support. 

Received November 9, 1967. 

1 Crook, K.,and Cook, P., J. Geol. Soc. Austral. ,13, 495 (1966). 

- Cook, P., J. Geol. (in the press). 

3 Boon, J., and Albritton, C, Fid. Lab., 5, 53 (1937). 

4 Dietz, R., Shatter Cones and Astroblemes., Trans. Lunar Geol. Field Con/., 

Bend, Oregon, 1965, 25 (Oregon Dept. Geol. and Min. Ind.) (1966). 
' Dietz, R., NASA Symposium on Shock Metamorphism in Natural Material" 

(in the press). 
6 Sun, J.. Trans. Amer. Geophys. Un.AS. 186 (1967). 



Reprinted from THE OIL AND GAS JOURNAL Vol. 65, No. 8 



16 



De Soto Canyon reveals salt trends 

Seismic-reflection profiles in Gulf of Mexico discover 
domal structures and a buried eroded slope. 



A 1963 reconnaissance seismic- 
reflection profile study by the 
USC&GSS Hydrographer, using a 
1,000-joule arcer, was made in the 
De Soto Canyon area of the north- 
eastern Gulf of Mexico. 

An apparent domal closure and 
shallow faulting were discovered de- 
spite poor penetration caused by 
equipment failure. 

During 1965, approximately 950 
miles of seismic reflection profiles 
were made by the Hydrographer in 
the De Soto Canyon area (Fig. 2) 
using the 1963 results as a guide. 
The 1965 study located five domes 
in the De Soto Canyon area and two 
more domes to the southwest near 
the 1,000-fathom depth curve. No 
major faulting was observed. 

A buried eroded slope, apparent- 
ly an old eroded shoreline, was dis- 
covered. Although the seismic-re- 
flection profiler studies were started 
primarily to determine the geology 
of De Soto Canyon, only the domal 
structures and the eroded slope will 
be discussed in this report, which 
will use the 1965 results exclusively. 

A 3,000-joule arcer, activated 
every 2 sec, supplied a broad-band 
sound source whose energy was con- 
centrated between 150 and 300 cps. 
The reflected returns were not fil- 
tered. 

A 14-ft hydrophone array with 
10 variable inductance hydrophones 
was towed 300 ft aft on the port 
side, and the arcer was towed 250 
ft aft on the starboard side of the 
ship at speeds varying between 6 
and 10 knots. Maximum penetra- 
tion was approximately 0.7 sec, or 
almost 2,000 ft assuming a velocity 
of 5,500 fps. Loran A provided 
navigation control. 

Geological age postulations. 

Groups of strata with a visible dif- 
ference in character are labeled A, 
B, C, D, and E in Figs. 3 through 7. 
No direct evidence is available for 
the age of the strata in the study. 
Project of the geology of Florida 
(Puri and Vernon, 1964) seaward 
and the extension of refraction data 




SHADED AREA shows salt trends and their possible extension into areas 
where domes have been located by seismic reflection study. Fig. 1. 



R. N. Harbison 

Environmental Science Services 

Administration 

Institute for Oceanography 

Silver Spring, Md. 

reported by Antoine and Harding 
(1965) for the northeastern Gulf of 
Mexico were used in the following 
age postulations: 

Group A strata — Pleistocene and 
Recent 

Group B strata — Pliocene-Pleisto- 
cene 

Group C strata — Upper Tertiary 

Group D strata — Lower or Mid- 
dle Tertiary 

Group E strata — Lower Tertiary 
or Upper Cretaceous 

Eroded slope. An eroded slope, 
complicating the strata correlations 
somewhat, crosses the area of study 
approximately between 29°27' and 
29°28'N latitudes and 86°31' to 
87°13'W longitudes. 

The slope probably extends east 
and west of the area of track-line 
coverage. This slope is buried be- 
neath the sea floor except for a 
short portion between 86° 5 3' and 
86°59'W longitudes which forms 
the anomalous east-west portion of 



northern De Soto Canyon. A report 
by Jordan (1951) contains a de- 
tailed bathymetric chart showing 
this east-west portion as the north- 
ern limits of De Soto Canyon. 

This east-west-trending slope is 
interpreted as a transgressing Ter- 
tiary shoreline which was eroded 
into Group D strata. Group E strata 
continue unbroken beneath this old 
shoreline indicating that the result- 
ing slope is not a fault scarp (Figs. 
4 and 6). 

Following the erosion of the Ter- 
tiary shoreline, sea level rose with 
respect to the land elevation and 
group C strata were draped over 
the slope east of dome 1. Group C 
strata thickened to the south and 
west forming the prominent reflec- 
tors seen above and on the flanks 
of domes 2, 3, and 4 (Figs. 4, 5, 
and 6). 

Group B strata were deposited 
under deeper water than group C 
strata completely masking the ex- 
pression of the old shoreline slope 
beneath the sea floor east of dome 1 . 

The seismic reflection profiles 
show the old buried shoreline to be 
approximately 500 ft deeper near 
87° 13' W longitude than at 86°31' 
W longitude suggesting that the 



124 



THE OIL AND GAS JOURNAL • FEBRUARY 20, 1967 



northeastern Gulf of Mexico has 
been subsiding more rapidly on the 
west than on the east. 

This east-west-trending Tertiary 
shoreline, appearing on or near the 
flanks of domes 1 and 2, will be 
elaborated on in the descriptions of 
Figs. 3, 4, and 6. 

Domal features. A family of five 
domes and six more features inter- 
preted as possible domes were lo- 
cated within the vicinity of De Soto 
Canyon. Two other domes were lo- 
cated near the 1,000-fathom con- 
tour west of De Soto Canyon 
(Fig. 2). 

The five domal features in the 
De Soto Canyon area were deter- 
mined by intersecting profiles. The 
six possible domes were indicated 
usually on a single trackline by one 
or more of the following: anomalous 
dip, apparent closure, shallow fault- 
ing, small localized graben. The cri- 
teria listed for possible domes are 
also present in the known domal 
structures found by intersecting pro- 
files. 

A north-south profile through 
dome 1 (Fig. 3) reveals a localized 
north-south fault extending north- 
ward from dome 1 through group 
D strata within the plane of the 
profile. A sea-floor expression of a 
rise approximately 200 ft high and 
2.000 ft wide above dome 1 ap- 
pears to be an erosional remanent 
of outcropping strata or caprock. 

If it is an outcrop, it is probably 
resistant group E strata. The ero- 
sional slope interpreted as an old 
shoreline lies on the south flank 
of dome 1. Most of D strata have 
been eroded away south of dome 1. 
Another cycle of erosion occurred 
following the deposition of group 
B strata eroding and reworking the 
groups B and C strata south of 
dome 1 . This same erosional cycle 




LOCATION of seismic reflection profile tracklines are shown here with 
domes 1 through 7 and possible domes 8 through 13. Contours of sea 
floor are in fathoms. Fig. 2. 



eroded B and C strata to form the 
east slope of the north-south por- 
tion of De Soto Canyon. Group A 
strata were deposited unconform- 
ably over this eroded surface. 

South of dome 1, group E strata 
appear to have been pierced by the 
dome, but have not been breached 
by the erosion which removed most 
of the younger group D strata. 

Fig. 4 is a northwest-southeast 
profile through domes 1 and 2. The 
group D strata have been pushed up 
almost to the sea floor on the north- 
west and southwest sides of dome 1 , 
truncated by erosion and covered by 
a thin layer of group A sediments. 

A slope extending from near the 
top of the southeastern portion of 
dome 1 down to a point approxi- 
mately halfway to dome 2 has been 
eroded into the group D strata. 
Southeast of this slope, only the 
lower one-third of group D strata 



SOUTH 




NORTH-SOUTH profile through dome 1. Fig. 3. 



survived erosion. The slope is the 
east-west trending Tertiary shore- 
line mentioned previously. 

Groups B and C thin rapidly on 
the northwest and southeast flanks 
of dome 2, suggesting that they were 
draped over the dome when it was 
a topographic high or that they 
were deposited contemporaneously 
with growth of the dome. 

Notice the comparison with the 
dip and thinning of groups B and 
C strata on the flanks of dome 2 
with the dip and thinning of group 
D strata on the northwest flank of 
dome 1 . 

It appears that group D strata on 
the northwest side of dome 1 were 
pushed up, while groups B and C 
strata were deposited during or after 
the uplift of dome 2. The center 
of dome 2 seems to have collapsed, 
causing a block approximately one- 
third the diameter of the dome to be 
dropped down into the center of 
the domal uplift. 

The strata on both sides of the 
down - dropped block have been 
bowed down causing apparent clo- 
sures in the shape of arches. 

Small local faults occur over 
dome 2 and on its flanks. A rather 
flat-topped expression shown by the 
deepest reflector may be the re- 
flection of a salt-sediment contact. 

A north-south profile (Fig. 6) 
through dome 2 shows the Tertiary 
shoreline on the north side of domal 
uplift. Group C strata are built out 



THE OIL AND GAS JOURNAL • FEBRUARY 20, 1967 



125 



SEC. 
0.4 



SOUTHEAST 

< 3.3 NAUTICAL MILES > 



NORTHWEST 



A NORTHWEST-southeast profile from dome 1 to dome 2. Fig. 4. 




over the slope eroded into group D 
strata and up on the north flank of 
dome 2, giving a false impression 
of a rim syncline. 

Group E strata seem to have been 
pushed up almost to the sea floor 
on the north side of dome 2 and 
sag into the center of the domal up- 
lift. Group C strata dip steeply 
away from the south flank of dome 
2 and probably overlie group E 
strata which is possibly too steep 
to give a reflected return. 

The same flat - topped reflector 
mentioned previously as a possible 
salt contact in the northwest-south- 
east profile is also present here, but 
with another reflector between it 
and E strata on the north, which 
may be caprock. 

An east southeast-west northwest 
profile through dome 3 (Fig. 5a) 
shows group C strata sagging down 
into the down-dropped center of the 
domal uplift causing arch-like struc- 
tures in group C strata over both 
sides of dome 3. The arch-like struc- 
ture on the west-northwest side of 
dome 3 has suffered faulting on 
both sides of its apparently closed 
portion. This closed portion has 
dropped down between these faults. 
The localized faults over dome 3 
reach up to very near the sea floor. 



Fig. 5b shows a north-south 
profile through dome 3. An expres- 
sion of a graben with localized fault- 
ing extending nearly to the sea floor, 
can be seen over the center of the 
dome. The group C strata are bowed 
down into graben as they were in 
Fig. 5a, but in a less pronounced 
manner. A possible salt-sediment 
contact in the shape of a dome lies 
approximately 0.6 sec below the 
sea floor in Fig. 5b. 

An east-west profile through 
dome 4 (Fig. 6) shows numerous 
small faults over the domal uplift. 
Group C strata have collapsed into 
the center of the dome especially 
on the east side, causing an appar- 
ent closure similar to those men- 
tioned in the descriptions of domes 
2 and 3. 

From near the center of dome 4 
westward, groups B and C strata 
have been truncated by erosion 
which formed the east slope of De 
Soto Canyon. A thin layer of group 
A strata unconformably overlie the 
truncated strata of groups B and C. 
A possible salt-sediment contact 
lies approximately 0.5 sec (approx- 
imately 1,400 ft) below the sea 
floor. 

Fig. 7 is an east northeast-west 
southwest profile from dome 1 



WEST-NW 

<30 NAUT. Ml-^ 



EAST-SE S ^ C 6 - [SOUTH 



SEAJLOOR 
BAT 




AN EAST southeast-west northwest profile through dome 3 (Fig. 5a, left), 
and a north-south profile through dome 3 (Fig. 5b, right). 



through the east-west portion of 
northern De Soto Canyon to dome 
5. Group E strata can be seen as 
an unbroken horizon between these 
two domes, indicating the absence 
of faulting along the north-south 
portion of De Soto Canyon at this 
point. 

A north northeast - south south- 
west profile through dome 5 shows 
the east-west erosional slope, which 
is interpreted as a Tertiary shore- 
line, north of the domal uplift. A 
graben and associated faulting ex- 
tends up from group E strata near 
the center of dome 5 to the vicinity 
of the sea floor. Strata have been 
bowed down adjacent to the graben. 

Fig. 8 is a profile through domes 
6 and 7 which protrude over 1,000 
ft above the surrounding sea floor. 
The direction of the profile changes 
from east-west to northeast-south- 
west over dome 6. Extremely rough 
weather caused the poor record 
quality. 

Dome 6 appears as a closed high 
on the USC&GSS chart 1115 at 
28°42' N latitude and 88°05' W 
longitude. It resembles an unburied 
version of the northwest-southwest 
profile through dome 2. 

Dome 7 appears as a closed high 
on a detailed bathymetric chart by 
Jordan (1951). It is located at ap- 
proximately 28°52' N latitude, and 
87°58' W longitude. A sea-floor de- 
pression southwest of dome 7 has 
a very steep slope on its southwest 
side in the first shallow reflector. 
The direct return from arcer to 
the hydrophone array occurs every 
2 sec and partially obscures the top 
of dome 7. 

Domes 1 through 5 in the De 
Soto Canyon area are interpreted 
as salt domes because of their size, 
shape, associated localized faulting, 
and graben over the crests. They 



126 



THE OIL AND GAS JOURNAL • FEBRUARY 20, 1967 




AN EAST-west profile through dome 4, left, and a north-south profile through dome 2, right. Fig. 6. 



resemble very closely the published 
data on known salt domes. 

The collapsing of sediments into 
the centers of domes 2, 3, 4, and 
5, along with the associated fault- 
ing which nearly reaches the sea 
floor, perhaps explains the depres- 
sions which form circular lakes over 
some salt domes in the marsh areas 
of South Louisiana. 

These closed depressions over 
shallow domes may provide the 
proper environment for the gener- 
ation of caprock and native sulfur. 

Domes 6 and 7, which protrude 
through the sea floor, are probably 
salt domes which are growing con- 
temporaneously with deposition of 
sediments. 

The possible-domes (8 through 
13) in the De Soto Canyon area 
may be salt domes, relict salt struc- 



tures, shale masses or fault struc- 
tures. It is likely that these fea- 
tures 8 through 13 are deep-seated 
salt structures. 

Possible extensions of known 
salt trends. Fig. 1 illustrates pro- 
jections of known salt trends into 
the areas of domal occurrence in the 
seismic reflection profile study area. 

The domes in the De Soto Can- 
yon area are in line with the East 
Texas, North Louisiana, Mississip- 
pi, and Alabama salt trend. Antoine 
(1965) reported a dome in the De 
Soto Canyon area, and another pos- 
sible salt structure aligned with the 
Pickens, Gilberton, and Pollard 
fault zone (the North Louisiana, 
Mississippi, and Alabama salt 
trend). 

The two domal features 6 and 7 



west of the De Soto Canyon area 
suggest that the South Louisiana 
salt trend may also extend into the 
De Soto Canyon area, forming a 
juncture with the northern salt 
trend. 

Bibliography 

Antoine, J. W. and J. L. Harding, "Struc- 
ture Beneath Continental Shelf, Northeastern 
Gulf of Mexico": Bulletin of the AAPG, 
Vol. 49, No. 2, 1965. pp. 157-171. 

Antoine, J. W., "Structural Features Under 
Continental Shelf off the Florida Panhandle 
Revealed by Seismic Reflection Measure- 
ments": Abstract; Geophysics, Vol. 30, No. 
6, 1965, p. 1,228. 

Puri, H. S. and R. O. Vernon, "Summary 
of the Geology of Florida and a Guidebook 
to the Classic Exposures": Florida Geological 
Survey, Special Publication No. 5, revised, 
1964. 

Jordan, G. F., "Continental Slope off 
Appalachicola, Florida": Bulletin of the 
AAPG, Vol. 35, No. 9, 1951, pp. 1,978- 
1,993. 



JlSrf; 



DOME NO. 1 




AN EAST northeast-west southwest profile from dome 1 to dome 5. Fig. 7. 





.,'■;; , =■- i . j:'f v ; if Li' 1> i*§ 

< 5.5 NAUTICAL MJLES*> ' '" jj I '■' r Jl'{ i{ ' ' 1 1 

L 



A PROFILE over domes 6 and 7. Fig. 8. 



lSI5JBiaJ3ISJ^(3JSMafaMSI3J2J3J2KJ^^ 

17 a 

Reprinted from PROCEEDINGS OF THE WORLD DREDGING CONFERENCE, 196^ 



a 



ENVIRONMENTAL EFFECTS OF DREDGING 
AND SPOIL DEPOSITION 

by 

W. HARRISON 

Land and Sea Interaction Laboratory 

Institute for Oceanography, ESSA 

Atlantic Marine Center 

Norfolk, Virginia 




GlfSJiiMa/SJEJeMe^^ 



535 



ABSTRACT 

The effects of dredging or associated spoil disposal 
are reviewed for two dredge operations in the lower 
Chesapeake Bay area. In one operation 1, 260, 000 cu. 
yds. of spoil were dumped from a hopper dredge on a 
target rectangle measuring 0. 5 by 1.0 naut. mi. , in 
water depths of 75 to 96 ft. Owing to the strong simi- 
larity in composition and size gradation of the spoil and 
natural bottom sediments, it was necessary to make 
an exhaustive sedimentological study of the dump area 
in order to identify concentrations of spoil. The most 
promising method for delineation of spoil utilized ano- 
malous profiles of sediment strength and void ratio, as 
determined from piston-core samples. Spoil disposal 
appeared to have only a transitory effect on the popula- 
tions of infauna and epifauna. Resettlement in both the 
areas of dredging and spoil deposition was very rapid, 
occurring by active migration of the animals and by the 
hydrodynamic distribution .of juvenile or larval stages. 
It was found important to differentiate between transitory 
high populations of juveniles at certain seasons and nor- 
mal faunal distributional patterns when attempting to 
assess the effects of dredging or spoil deposition on 
benthic organisms by means of "before" and "after" fau- 
nal surveys. 

Precise monitoring of possible spoil buildup on an 
oyster ground near a spoil outfall was accomplished by 
repeated diver measurements of the distance from 
the water-sediment interface to the tops of steel refer- 
ence rods located along the perimeter of the oyster 
ground. Details of the field procedures are presented. 
Because the observed bottom fluctuations can be attri- 
buted exclusively to natural variations in erosion and 
deposition, the data presented constitute a useful refer- 
ence on the variability in bottom level to be expected in 
the absence of spoil-induced sedimentation. The varia- 
tions are of the order of a few millimeters per week. 



537 



INTRODUCTION 

The questions most frequently asked by those con- 
cerned with environmental pollution by dredging activity 
have to do with the effects of dredging or spoil deposi- 
tion on the local marine life. Most concern is usually 
directed toward the marine organisms found upon or 
within the bottom in the affected areas, rather than to- 
ward the organisms in the water column itself. The 
problem of documenting such effects usually resolves 
into obtaining adequate data on changes in local bottom 
elevations, suspended sediment concentrations, and 
animal populations. What may be considered adequate 
data for one study will quite often be irrelevant for an- 
other, due basically to differing requirements or envi- 
ronmental conditions. It is the purpose of this paper to 
review two recent studies that were designed to deter- 
mine the effects of dredging or spoil disposal on benthic 
organisms in lower Chesapeake Bay. At two of the sites 
(fig. 1, A and B) there was significant damage to faunal 
populations. At sites C and D damage was anticipated, 
but failed to materialize. The monitoring techniques 
developed for the last two sites should prove useful, how- 
ever, and the data on natural variability in bottom ele- 
vations may provide helpful reference material for 
studies in which variations in spoil-induced bottom 
changes approach variations due to natural causes.. As 
the body of such case histories grows, it becomes pro- 
gressively easier to develop rational design criteria for 
each successive monitoring study. Eventually, those 
involved in specifying restrictions on the activities of 
dredging or spoil deposition will have a reasonably ade- 
quate base upon which to work. 



DREDGING AND SPOIL DEPOSITION IN OPEN BAY 

WATERS 

In connection with a 1961 dredging project on the 
Rappahannock Shoal (fig. 2), the Corps of Engineers, 
U. S. Army, dumped 1, 260, 000 cu. yds. of spoil on a 
target area six to ten nautical miles from the dredged 
area, over a two-week period. This target rectangle 
measured 0. 5 by 1. naut. mi. , and water depths were 
between 75 and 96 feet. A contract between the U. S. 



538 



Army, Corps of Engineers, and the Virginia Institute of 
Marine Science (VIMS) provided an instrument for in- 
vestigating the effects of the spoil dumping in the target 
area, and numerous investigations were carried out by 
VIMS personnel in "before" and "after" surveys of the 
sediments and animal populations in the area. Many of 
the important results and conclusions of the sedimento- 
logical and faunal surveys are described elsewhere 
(Harrison, and others, 1964). 

The most difficult problem encountered in the study 
was that of locating concentrations of spoil. The spoil 
material consisted largely of sandy silt and it was 
dumped in an area also composed dominantly of sandy 
silts. Sediment mineralogy was of little help in identi- 
fying spoil, owing to its uniformity within the entire 
area of investigation. Bulk chemical composition like- 
wise proved inadequate for spoil differentiation. 

In seeking a way to delineate areas of spoil bottom 
it was noted that the dumping process might load the 
bottom sediments and cause shear failure in them if the 
stresses were of sufficient magnitude. Resulting slumps, 
flows, or settlings of the bottom materials could be dis- 
cerned by strength and void- ratio anomalies or, in cer- 
tain cases, by bottom contours. 

As commonly reported in the literature of soil 
mechanics, concerning natural, normally-consolidated 
silty sediments, the relation between undrained shear 
strength and effective stress is constant for a given soil. 
Thus, the strength must increase with depth if an equi- 
librium exists in the sediment. Examination of shear 
strength data (Harrison, et al. , 1964, table 3) from a 
suite of piston cores from the area of spoil dumping re- 
vealed that strength did increase with depth inmost 
cores. One core, however, displayed a distinctly ano- 
malous strength profile. 

A parallel examination of void- ratio data for the 
core samples revealed that certain cores displayed 
anomalies in the expected reduction of void- ratio with 
depth. These anomalies are shown in figure 3 as curves 
1, 2, 3, and 4. The minimum thickness of the spoil, at 
the two stations where positive identification was made, 



539 



was probably 10 cm. Various data suggested that the 
maximum thickness was only about 40 cm. Hydrogra- 
phic surveys of the spoil disposal area did not reveal 
any obvious highs or lows on the bottom. This was pro- 
bably because the bulk of the spoil was spread thinly by 
the prevailing currents over a relatively wide area. 

Once the areas of spoil had been established by the 
use of the strength and void- ratio data, it was possible 
to examine the effects of the deposition on the infaunal 
populations. Variations in the numbers of animals and 
species present at the two spoil-disposal stations, be- 
fore and after dredging, are shown in figure 3. The 
animal collections taken one month after dredging show 
a marked decrease in numbers of animals and species. 
Harrison, et al. (1964, p. 752) did not believe the 
decrease was related to seasonality in the animal popu- 
lations. Nephtys incisa, a worm, was the most preva- 
lent animal of the species found at the two stations one 
month after dumping of the spoil. Because of the very- 
active nature of this worm, it probably migrated to the 
area, immediately after spoil deposition. Juvenile 
mollusks, particularly Ensis directus (692 individuals) 
made up a large part of the population in the faunal 
sampling made six months after spoil dumping, indica- 
ting that hydrodynamic factors were effective in reset- 
tling the spoil-disposal area. The large numbers of 
animals present six months after dredging and spoil 
dumping in part reflects seasonal effects in faunal fluc- 
tuations. A final sampling made 15 months after spoil 
deposition indicated successful recovery of animal 
populations in the spoil area. 

The effects of dredging on a population of infauna 
can be examined by reference to the curves on figure 4 
for a station located within the dredged channel (fig. 2). 
In the sampling done one month after dredging a marked 
decrease in both total numbers of animals and species 
was found. This decrease was much greater than could 
be accounted for by seasonality alone. Nephtys incisa 
made up 7 5 percent (6 individuals) of the population. 
Recovery of the infaunal population was relatively com- 
plete after a lapse of only six months (fig. 3). 



540 



These and other data indicate that while dredging 
and spoil disposal in the two areas temporarily destroy- 
ed the infaunal populations, resettlement and recovery 
were fairly rapid. The resettlement occurred by mi- 
gration of active species and by hydrodynamic distribu- 
tion of many species while in the free- swimming or 
free-floating larval stages. 



SPOIL DISPOSAL IN PROXIMITY TO AN ESTUARINE 
OYSTER GROUND 

The author was requested to design a study to moni- 
tor the buildup of sediment on an "oyster ground" in the 
York River estuary, in response to anticipated spoil 
deposition from an outfall (fig. 5, inset) located 0. 8 to 
2. miles in a down-estuary direction. Also requested 
was an analysis of the effects of the changes in bottom 
elevation on oysters living within the leased area (fig. 5). 
Because a suit over damage to the grounds could have 
been involved, three considerations seemed of impor- 
tance: 

1) The measurements would have to be pre- 
cise. (Fathometer surveys, accurate to 
± 0. 2 ft. , at best, would be inadequate). 

2) The measurements would need to be nu- 
merous enough both temporally and 

spatially to permit adequate descrip- 
tion of variations in the location and 
extent of spoil buildup. 

3) The biological and sedimentological inter- 
pretations of the data would have to stand 
up in court. 

In regard to the last consideration, it was necessary 
to employ the services of a diver who was also a marine 
biologist familiar with oyster ecology. 



541 



Materials and Methods 

Steel reference rods were placed at 80 stations 
(fig. 5) around the perimeter of the lease property. 
Horizontal control was provided by the U. S. Army, 
Corps of Engineers, and was based upon the official 
plat of the oyster lease. The Corps survey team placed 
markers at the seven corners of the property and at 
certain intermediate stations along the lease boundary 
lines. A field crew then placed pound poles at 300-foot 
intervals around the perimeter of the property, but five 
feet to the outside of the surveyed lease boundaries. 

The steel reference rods were positioned by means 
of a graduated line stretched between successive pairs 
of pound poles. Seventy-three reference rods were 
equipped with an 18-inch- square metal plate located 
several inches from the top of the rod (see inset, fig. 5). 
The plates prevented the rods from sinking into the bot- 
tom at those few stations where the bottom was very 
soft. (As explained below, it was later found that the 
plates were unnecessary at most stations. ) Rods were 
"planted" in the bottom by removing an 18-inch square 
of sediment to a shallow depth. Once the plate was in 
the pocket, it was covered again with the sediment that 
had been removed originally. Thus, the tops of the rods 
projected above the bottom some one to five inches after 
planting. 

Measurements of changes in bottom level were 
taken by a two-man team consisting of a diver and a 
helper in a skiff. (A gasoline-powered air compressor 
supplied air to a reserve tank from which the diver drew 
air via a hose). A steel carpenter's rule with an ad- 
justable right-angle arm containing a level bubble was 
used to measure the distance from the top of each re- 
ference rod to the sediment surface (fig. 6). The 
distance was locked by means of a tightening screw, and 
the rule was passed to the helper in the skiff who im- 
mediately recorded the distance, station number, and 
any of the diver's observations. 

Nine rods were planted without plates, in order to 
obtain an estimate of the vertical stability of such re- 
ference rods in a relatively firm bottom. Such rods 



542 



proved stable, as indicated by later statistical analysis 
of the elevational data for adjacent rods with and without 
the stabilizer plates. At stations 39 and 57, two refer- 
ence rods were emplaced to obtain an estimate of the 
variability in sedimentation to either side of a pound- 
pole marker stake. Differences noted between rod 57 
and 57A (table 1) are more apparent then real because 
the plate on rod 57 limited erosion of the bottom during 
the period December 4-19, 1965. 

The condition of the bottom in the lease area was 
determined before and after the dredging and spoil dis- 
posal by means of a visual inspection. Those areas of 
the bottom visible from the surface were examined from 
a skiff either drifting with the current or driven slowly 
over the area. Occasional dives were made to determine 
bottom texture and consistency. Deeper areas, not 
visible from the surface, were examined by the diver 
while drifting with the current or fastened to a drifting 
skiff. The helper in the skiff kept track of the position 
of both the boat and the diver. 

In addition to the visual inspections, 650 oysters 
obtained commercially from York River beds were 
planted at station 45 (fig. 5), six days before the dredg- 
ing and spoil pumping commenced. This was done in 
order to have a measure of any deleterious effects that 
dredge spoil might have on living oysters, should the 
spoil material move upstream from the area of spoil 
outfall (fig. 5, inset). The oysters were recovered and 
examined a few days after final measurements of bottom 
level. 

Results 



The results of the field program are given in table 
1. Three sets of measurements of the elevation of the 
bottom were made before commencement of dredging 
(December 10, 1965), two complete sets and part of a 
third were made during the dredging period, and three 
sets were made after dredging ceased (January 4, 1966), 

A severe winter storm occurred in Virginia during 
the latter part of January and early February, 1966, 



543 



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546 



which resulted in the formation of extensive ice floes in 
the York River. These ice floes removed several of the 
pound poles along the northern boundary of the study 
area. Reference rods adjacent to these poles could not 
be located after the storm. In addition, the action of the 
ice disturbed a few of the shallow reference rods. As 
a result, only one or two "after dredging!' measurements 
were made at some of the reference rods. These are 
indicated in table 1. 

The visual inspection of the study area made before 
the commencement of dredging revealed that the shal- 
lower areas were covered with extensive beds of eel 
grass (Zostera marina) and associated epiphytic algae. 
No oyster reefs were found in the shallow areas. 

The deeper areas were generally free of vegetation. 
The bottom materials consisted of silt and the bottom 
was soft. There was a one-half to three-inch layer of 
extremely fine, loose sediment overlying either soft, 
slightly firmer sediment or accumulations of dead shell. 
There was a fair-sized population of the hard clam 
( Venus mercenaria ) in the top few inches of sediment. 
These clams averaged two to three inches in width. 

Oyster reefs were found only in the northwest corner 
of the lease area and at scattered intervals along the 
line between stations 21 and 25 (fig. 5). These reefs 
were of very limited size and consisted of both living 
oysters and dead shell. None of the material on the 
reefs was handled by the diver. 

The appearance of the bottom at the time of the 
final swim over (12-13 March 1966) was identical to that 
at the time of the initial swimover. This was expectable, 
however, in view of the fact that dredging downstream 
was unexpectedly cut short and only a very small amount 
of spoil entered the York River at the outfall. None of 
the spoil-polluted estuarine water was observed moving 
as far upstream as the oyster lease. 

A total of 582 of the 650 oysters planted in the vi- 
cinity of station 45 were recovered on 12-13 March 1966. 
(The remaining 68 oysters could not be located because 
of limited visibility). Of these, 26 (4.4 percent) were 



547 



boxes (no oyster meat within shell; shell sometimes 
filled with sediment), six (1. percent) were gapers 
(animals within the shell were too weak to keep the shell 
closed in air), 12 (2. 1 percent) were strong enough to 
keep the shell tightly closed but did not appear healthy 
enough to eat. The 538 remaining oysters (92. 5 per- 
cent) appeared to be in excellent condition and were 
eaten by several persons after being prepared in a 
variety of ways. A summary of the oyster data is 
presented in table 2. Although no quantitive estimate 

Table 2. Summary of data obtained from oysters 
maintained at the periphery of the study 
area (in the vicinity of station 45) during 
the period 4 December 1965 to 13 March 
1966. 





Numbe r 


Percent 








total 


Percent 






planted 


total 








recovered 


Oysters planted 


650 


100 




Oysters recovered: 








a. Healthy oysters 


538 


82.9 


92. 5 


b. Gapers 


6 


0.9 


1. 


c. Other* 


12 


1.8 


2. 1 


d. Total live 


556 


85. 6 


95. 6 


e. Boxes 


26 


4. 


4.4 


f. Total recovered 


582 


89. 6 


100 



Unrecovered: 68 10.4 

* Animals strong enough to close shell in air, but did 
not appear healthy enough to eat. 

was made, many of the oysters recovered had healthy 
spat attached to them, measuring about one inch across, 
Spat this size had not been noticed during the planting 
operations. 

Information such as the above, for oysters planted 

to determine the effects of spoil deposition or lack 

of it, is valuable for the determination of damages and 



548 



awards in courts. This is true if the information re- 
presents the expert evaluation of a marine biologist 
knowledgeable in oyster ecology. 

Discussion 

A study of the net changes in the bottom elevations 
(table 1) during the entire period of observation reveals 
that the perimeter of the oyster lease was undergoing 
erosion almost everywhere between stations 1 and 44 
(fig. 5). The following stations along the perimeter 
nearest the dredge spoil outfall (fig. 5) showed net 
accretion during the period 27 November 1965 through 
12 March 1966: stations 45, 46, 47, 48, 50, 54, 55, 56, 
57, 61, 65, 67, 70, 72, and 73. Of these stations, the 
following ones exhibited no change or net erosion during 
the period of dredging: 47, 50, 55, 56, 61, 70, 72, and 
73. This indicates that the slight amount of deposition 
observed over the entire period at stations along the 
southern perimeter was not directly related to deposi- 
tion of dredge spoil, but to natural sedimentation in the 
area. 

Review of the net changes in bottom level during the 
period of dredging (table 1) reveals that at 59 measure- 
ment points there was no net change or that the bottom 
was being eroded. At 23 stations the bottom was build- 
ing up. The amounts of buildup and erosion were in 
almost all cases negligible (less than one -half inch). 
At only one station, number 28*, was the net or the 
weekly deposition greater than one-half inch. It is only 
logical to presume that similar conditions of bottom 
erosion, bottom stability, and very slight and sporadic 

When the stake and plate at station 28 were removed, 
it was found that amphipod tubes extended from the sur- 
face of the sediment to the plate. These tubes were very 
closely packed together. During the swimover on the 
following weekend, it was noticed that patches of the 
bottom containing amphipod tubes were raised slightly, 
relative to adjacent bottom that did not have these tubes. 
The parts of these tubes that extend above the surface 
probably act as a sediment trap and, as the sediment 
accumulates, the animal builds its tube higher to keep 
pace with the rising sediment surface. 



549 



bottom deposition existed over the area of the entire 
oyster lease during the period of dredging and spoil 
outfalL The changes in bottom level observed during 
the period of dredging were in all probability natural 
changes, the effect of dredge-spoil outfall, if any, being 
too minute to be discerned. 

Conclusions 



The overall trend in sedimentation along the peri- 
meter of the oyster lease before, during, and after the 
dredging was one of slight erosion. There was only 
very slight deposition over limited areas within the 
leased property during any of these three periods and 
such deposition was confined to MLW depths of less 
than three feet. The changes in bottom level would in 
no way have been detrimental to live oysters on the 
bottom within the lease area. Mortality within a group 
of planted oysters held just outside the study area, on 
the perimeter closest to the dredging operation, was 
very low. This mortality was probably entirely natural 
and not due to the dredging operations. Thus, it was 
concluded that dredging and spoil disposal had no ob- 
servable effect on the character of the river bottom or 
the natural animal population within the survey area. 



BUCKET DREDGING IN PROXIMITY TO AN ESTUARINE 

OYSTER GROUND 

The author and a marine-biologist diver conducted 
a monitoring program similar to that described above 
in Hampton Roads, Virginia (area D of figure 1). The 
concern in this study was that the activity of a bucket 
dredge, operating in the entrance to Hampton Creek, 
would produce a deleterious buildup of silt on an adja- 
cent oyster ground (fig. 7). It was important to know 
the extent of damage to the natural "rock" (shell sub- 
strate on which oyster larvae "set"), and to the living 
oysters present, as a result of silt deposition from the 
disturbed bottom in the dredged channel. 

As in the York River study, it was concluded that 
the oyster ground was not damaged in any way by the 
dredging. Data on the changes in bottom elevation due 



550 



to natural causes will be released to interested research- 
ers upon request. 

SUMMARY 

The studies reviewed show that if the design and ex- 
ecution of a monitoring program are carefully done, it 
is possible to make precise statements about the effects 
of dredging or spoil deposition on changes in bottom 
elevation or on the populations of bottom -dwelling organ- 
isms in the affected areas. Where litigation over 
damages to the bottom organisms or the substrate upon 
which they live may be involved, it is desirable to have 
monitoring programs designed and executed by the same 
marine scientists who will evaluate and interpret the 
data. Reviews of other studies, such as the two pre- 
sented here, should be published in order to aid the 
advancement of environmental studies of pollution by 
dredging and related spoil disposal. 

ACKNOWLEDGMENT S 

Mr. M. P. Lynch, Virginia Institute of Marine Science, 
acted as the marine-biologist diver for the three studies 
and Dr. M. L. Wass, also of VIMS^provided the faunal 
lists used in the reference cited below. 

REFERENCE 

HARRISON, W. ; LYNCH, M. P. ; ALTSCHAEFFL, A. G. , 
1964, Sediments of lower Chesapeake Bay, 
with emphasis on mass properties: Jour. 
Sedimentary Petrology, v. 34, p. 727-755. 



551 



Figure List 

Map showing sites in lower Chesapeake Bay where 
environmental effects of dredging and spoil disposal 
were studied. 



2. Map showing dredged area on Rappahannock Shoal 
and site of spoil dumping from hopper dredge. 



3. Void-ratio reduction with depth in five piston cores 
from the area of spoil dumping. Curves 1-4 show 
anomalous profiles. Curve 5 shows an expectable 
curve for bottom sediments that have not been sub- 
jected to a load of spoil. ( Data from Harrison, et al., 
1964, fig. 8, cores 17a, 17b, 20a, 20b, and 22. j~~ 



4. Variation in numbers of animals and numbers of 

species present in grab samples taken in the dredge 
area ( one station) and in the spoil disposal area (two 
stations) before and after dredging. 



5. Layout of stations for determination of changes in 
sediment level along perimeter of an oyster lease, 
lower York River estuary. 



6. Method of making underwater measurement of depth 
to water-sediment interface, using top of steel rod 
as reference level. 



7. Location of a study of the effects of dredge-induced 
siltation on an oyster ground near an area of bucket 
dredging. 



552 




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SPOIL DISPOSAL AREA 



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6 MONTHS 
BEFORE 



1 MONTH 
AFTER 



6 MONTHS 
AFTER 



15 MONTHS 
AFTER 



TIME RELATIVE TO DREDGING AND SPOIL DISPOSAL 



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18 



Reprinted from MARINE GEOTECHNiaUE, University of Illinois Press, Urbana 



PLATE-LOAD TESTS ON SANDY MARINE SEDIMENTS, LOWER CHESAPEAKE BAY * 

W. HARRISON** AND A. M. RICHARDSON, JR.*** 

ABSTRACT 

Two plate-bearing tests (similar to ASTM D 1196-57) were made 1.8 nautical 
miles west of Little Creek Harbor entrance in 16 to 20 ft (5 to 6 m) of water. 
A Ul-ton (3T»000 kg) load frame was constructed to ensure adequate reaction for 
each jack load. The load frame was emplaced by the USS Salvager , a U.S. Navy 
rescue-salvage vessel, and divers from the ship conducted the tests according 
to telephoned instructions from the deck. 

Bearing capacity factors (N ) for use in Terzaghi's bearing capacity equa- 
tion were estimated at 62 for site A and 195 for site B. These factors are 
somewhat higher than would have been estimated on the basis of triaxial tests on 
the sand. Average coefficients for subgrade reactions of 50 tons per cu ft and 
110 tons per cu ft were obtained at site A and site B, respectively. These 
values compare favorably with values proposed for medium to dense submerged sands 

It is concluded that future research should be directed toward the develop- 
ment of a standard penetration sampling test for use in the marine environment. 
This test should be calibrated against further in-place load tests. 



INTRODUCTION 

Many marine engineering projects 
that will be undertaken in the immedi- 
ate future will involve placement of 
structures on surficial sediments of 
the continental shelves. Although the 
configurations and functions of the 
structures can be expected to vary 
greatly, their placement for the most 
part will be limited to shelf areas 
having depths less than 180 m 
and covered by sandy marine sediments. 
Consequently, the design and fabrica- 
tion of suitable submarine structures , 
and the ultimate success of many proj- 
ects, will depend largely on accurate 



Contribution number 5 of the Land and 

Sea Interaction Laboratory. 

**Land and Sea Interaction Laboratory, 

Institute for Oceanography, ESSA, 

Norfolk, Virginia. 

***Department of Civil Engineering, 

University of Pittsburgh, Pittsburgh, 

Pennsylvania. 



foreknowledge of the load-carrying 
capacity of sandy marine sediments. 

A better understanding of the 
ultimate bearing capacity and settlement 
behavior of submarine sands is required 
to proportion properly the base-plate 
foundation elements of submarine struc- 
tures, to predict the relationships of 
structural load and rate of settling, 
and to make allowance for dynamic re- 
sponse behavior (such as natural 
frequency) of completed structures. 
This knowledge can be gained only by 
in-place investigations of marine sedi- 
ments. These investigations are limited 
further by the need to conduct them 
easily and reliably from shipboard in 
water depths encountered over the conti- 
nental shelves. This paper provides 
background information about foundation 
investigations in sandy marine sediments 
and presents the results of preliminary 
research directed toward the design of 
a simple method for submarine foundation- 
site investigation. 



274 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 275 



LOAD-CARRYING BEHAVIOR OF SANDS 

For convenience, the determination 
of the load-carrying behavior of sur- 
face foundations on sands is usually 
considered as two separate problems: 
(l) the determination of the load at 
which ultimate failure will occur 
and (2) the determination of the 
settlement of the foundation under any 
load less than failure. 

Both aspects of foundation behavior 
are influenced by the structural design 
of the base and the properties of the 
soil. The load-carrying behavior of 
bases on sand is a function of the base 
size, the base geometry, the distribu- 
tion of the load on the base, and the 
flexibility of the base. It is also 
a function of the angle of internal 
friction of the sand, $ , the relative 
density of the sand, D r , and whether 
the sand is dry, moist, or submerged. 
The friction angle of the sand is 
influenced by the void ratio, grain 
size distribution, grain geometry, and 
mineral composition of the sand; and to 
a lesser degree it is influenced by 
the wet or dry condition of the sand 
and rate of load application. In 
addition, the method of testing 
(whether triaxial, direct shear, or 
plane strain) has been shown to have 
a marked effect upon the friction angle. 



DETERMINATION OF ULTIMATE CARRYING 
CAPACITY 

Terzaghi (19^3) presents a solution 
for the ultimate carrying capacity of 
foundations on sand. This solution is 
based on limiting equilibrium along 
two failure surfaces approximating 
logarithmic spirals, and yields, for 
uniformly loaded circular areas, 



where 



L ult 



L ult 



= 0.6yRN 
Y 

= ultimate bearing capacity 

= total unit weight of sand 
above water or the 
buoyant unit weight of 
submerged sand 



R = radius of loaded area 

N = dimensionles s bearing 
Y 

capacity factor. 

Terzaghi (19^3, p. 125) has plotted 
N versus the friction angle of the 
sand for two extreme conditions, general 



shear and local shear. For local shear 
it is assumed that a failure of the load 
area occurs before full mobilization of 
the shear strength on the failure sur- 
faces has occurred. Sowers (1962) has 
suggested that the general shear analy- 
sis be used for relative densities over 
TO percent and the local shear analysis 
for relative densities less than 20 
percent. Interpolation between these 
extremes on the basis of relative den- 
sity is suggested. 

Values of <\> can be determined by 
laboratory shear tests at field void 
ratios and eonfining pressures. This 
requires a knowledge of field void 
ratios. Special and costly techniques 
are necessary for obtaining undisturbed 
samples of sands. More commonly, both 
<(> and the relative density are estimated 
from the results of the Standard 
Penetration Test, in which a lUO-lb 
weight is dropped 30 in. onto a 2-in. 
(outside diameter) split-spoon sampler. 
A plot of Ny versus the results of 
standard penetration tests is given in 
Peck and others (1953, p. 222). This 
plot is commonly used in designing 
foundations for sands on land. 



DETERMINATION OF LOAD-SETTLEMENT 
BEHAVIOR 

The load versus settlement behavior 
of loaded areas on sands requires 
considerable study. Methods for deter- 
mining or estimating this behavior have 
been suggested as follows: 

(1) results of the Standard Pene- 
tration Test ; 

(2) results of field loading tests; 

(3) results of consolidation tests 
(one-dimensional compression tests) and 
elastic stress analyses; and 

(k) triaxial test results and an 
elastic stress analysis akin to the 
method for estimating settlements of 
foundations on clays. 

Method 1 is the easiest to apply. 
Method 2 must rely upon an incomplete 
knowledge of the relationship between 
load settlement behavior and the dimen- 
sions of the loaded area. Method 3 can 
be used to assess the effects of sub- 
mergence on the sands but neglects 
settlement resulting from lateral strain 
of the soil element. Method h, although 
it requires considerable detailed testing, 
accounts for settling caused by lateral 
strains and can be used for either sub- 
merged or dry sands. It is deficient in 
that it places too great a reliance 
upon an elastic stress analysis. 



276 



Marine Geotechnique 



The common procedure for land- 
based foundations on sands is to use 
the results of the Standard Penetration 
Test and a graph prepared by Terzaghi 
and Peck (19^8), reproduced in Figure 
1. The suggestion is made by Terzaghi 
and Peck that the pressure for any 
given settlement be halved to consider 
submergence. Sowers and others (1966) 
questioned the validity of this 
reduction . 



LOAD-CARRYING BEHAVIOR OF MARINE SANDS 

From the above discussion it seems 
apparent that a reliable and reasonably 
convenient method for determining the 
load-carrying behavior of ocean bottom 
sands does not exist. Among the prob- 
lems encountered are the following. 
First, it is difficult to obtain un- 
disturbed samples of submarine sands. 
Second, the Standard Penetration Test 
might be performed in shallow water, 
but its use in moderately deep water 
would be almost impossible. Finally, 
underwater load tests are generally 
too cumbersome for practical applica- 
tion. In an attempt to solve some of 
these problems, the authors designed 
load tests similar to those used in 
subaerial environments and conducted 
in-place tests on sandy marine sedi- 
ments in the lower Chesapeake Bay. 
Differences were studied in the loading 
characteristics in submarine and sub- 
aerial environments and standard load 
test data were made available for two 
sites. The standard data can be used 
to compare the results of future in- 
place load tests in the same area and 
to calibrate the instruments used in 
such test s . 



LOAD TESTS 



LOAD FRAME 

A Ul-ton (37,195 kg) load frame 
(Figure 2) was constructed using steel 
and concrete. Six U.S. Coast Guard 
concrete buoy sinkers, each weighing 
^,737 kg (12,700 lbs) provided most of 
the mass of the frame. The design was 
dictated in part by the necessity for 
a crane transfer from the dock where 
the frame was fabricated to a pick-up 
point (in air) where the frame could 
be secured (Figure 2) to the open 
shackles of the cables of the USS 
Salvager . These cables were 5-^ m 
apart, center to center. 



EQUIPMENT 

Three 2 . 5-cm- (l.0-in.-) thick 
steel plates, having diameters of 30.0, 
1+7.5, and 60.0 cm (12, 19, and 2U in.) 
were used. Small handles (Figure 3) 
were welded near the perimeters of each 
plate to aid in handling by divers. A 
calibrated hydraulic jack having a 
maximum capacity of 10 tons and an 
excursion of 20 cm was used. The datum 
beams for the dial gauges were 255 cm 
long and stood on legs 20 cm high. 
Standard dial gauges with 3.5-cm-diam- 
eter faces were mounted in plexiglass 
chambers (Figure 3) filled with mineral 
oil. Thin rubber sheets protected the 
dial pin arms. A schematic diagram 
and photograph of the test setup are 
shown in Figure 3. 



TEST SITES 

The two submarine sites of Figure 
h were chosen for the plate tests be- 
cause of the uniformly smooth sandy 
bottom over short distances in the area, 
and because the waters of this part of 
Chesapeake Bay have relatively low con- 
centrations of suspended solids. Phys- 
ical properties of the sediments at 
test sites A and B are given in Table 1, 
together with water temperature, salin- 
ity , and mean water depth. The tidal 
range in the area is 0.76 m. 

Sediments at depth at site A were 
sampled with a Chesapeake Bay Insti- 
tute piston corer (Silverman and Whaley, 
1952); as modified by Harrison (Harrison, 
Lynch, and Altschaeffl, 196U , p. 730). 
The results of size analyses and sedi- 
ment profiles are shown in Figure 5. 
Failure to recover sediment after full 
penetration with the 2.0-m core barrel 
at site B makes us certain that sand 
is present to a depth of at least 2.0 
meters below the bottom. A special 
piston-core sample of the upper 20 cm 
was taken to determine the void ratio. 

The mechanical properties of 
cohesionless sediments depend almost 
entirely on their relative density, D r . 
For this reason the description of 
such a sediment is inadequate unless it 
contains reliable information concerning 
its relative density. The D values of 
Table 1 required the determination of 
the in-place void ratio. Void ratios 
were approximated by measurements made 
on cores taken by the modified Chesapeake 
Bay Institute piston corer and retained 
in plastic core liners for transport to 
the laboratory. Soil profiles (Figure 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 277 









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278 Marine Geotechnique 

5) at sites A and B give the D r values the 30.0 cm plate resulted in severe 

where determined. disturbance. The divers attempted to 

jack to an excessively high initial 
load. After completion of the loading 

TEST PROCEDURE of the two larger plates, the load 

frame was moved 6 m north of its 

After the ship had made a three- original position and the 30.0 cm plate 

point anchor at each site, the load was loaded. 
frame was slowly lowered to the bottom, 
and as soon as it was placed the 

lowering cables were slackened. This RESULTS 
procedure was followed to prevent any 

disturbance to the frame from heaving The results of the load tests at 

of the ship. sites A and B are plotted in Figures 

Two SCUBA divers examined the 6 and 7. The plotted penetration 

bottom and the attitude of the frame usually is the average of the readings 

at each site. At each test site the taken at the three points on each 

bottom was roughly horizontal and small plate. In a few instances one of the 

ripple marks were noted. At site A readings given by the diver would be 

the concrete base blocks sank k . and obviously in error. This reading was 

7.6 cm into the sand. At site B, both discarded and the average of the other 

blocks sank 2.5 cm. two was plotted. Tilting of a plate 

After the pressurized dial gauges, was not significant until the highest 

jack,i load plates, underwater floodlight, load increments. 

and the beams for mounting the dial Estimates of resultant ultimate 
gauges had been lowered to the SCUBA bearing capacities are tabulated in 
divers, a hard-hat diver in telephone Table 2. These estimates are somewhat 
communication with the deck was put arbitrary and were obtained by inter- 
over. The SCUBA divers positioned the secting s t rai ght -1 i ne-f i t s to the low- 
30-cm-diameter plate, jack, reaction pressure and high-pressure portions 
beams for the dial gauges, and a shim of each lead-deflection curve (Figures 
between the jack and the jacking member 6 and 7). 

of the load frame. Dial gauges were Average values of coefficients of 

then attached to mounting rods. These subgrade reaction as suggested by 

rods were screwed into the load plates Terzaghi (1955) were estimated (Table 

near their perimeters and spaced 120 de- 3) assuming linear load versus settle- 

grees apart. As the plate was jacked ment behavior to 1/2 ton per sq ft 

into the sediment the gauge-pin arms (1000 lbs per sq ft) at site A and 1 ton 

bore upon the rigid reaction beams whose per sq ft (2000 lbs per sq ft) at site B. 

feet extended well beyond the area of Average values of this coefficient were 

disturbance. Each gauge was numbered. 50 tons per cu ft at site A and 110 

After the hard-hat diver had jacked the tons per cu ft at site B. 
plate to a given load, and upon instruc- 
tion from the deck, he would read one 

gauge and signal the two SCUBA divers DISCUSSION 
to write the dial readings of the two 
other gauges on their slates. The three 

gauge values were then read to the ULTIMATE BEARING CAPACITIES 
scientist on deck by the hard-hat diver. 

Additional shims were added during the Values of ultimate bearing capacity 

tests as necessary, but this in no way were calculated according to Terzaghi 

influenced the test results. and Peck (19U8, p. 172) and appear in 

The small and medium load plates Table 2. These values were calculated 

were always positioned beneath jacking assuming 6l lbs per cu ft as the buoyant 

members at either end of the load frame. unit weight of the sand, for <$> values 

This left the greatest reaction for the of 35 degrees and Uo degrees and for 

large load plate, when it was positioned the local shear and general shear cases, 

beneath the central jacking member. No Specimens of the sand from site B were 

difficulties were encountered in the tested in drained triaxial compression, 

overall procedure. Wave action was The results of these tests appear in 

practically nil during the tests and Figure 8. From these tests, <j> at 

tidal currents always less than about site B was determined to be 38 degrees. 

0.5 m/sec. Thus it can be seen that, at site B, 

At site A, the initial setup of ultimate bearing capacities in excess 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 279 

TABLE 2. 
ULTIMATE BEARING CAPACITIES (LB/FT 2 ) 



Plate 
Dia. 
(ft) 



General 
Shear 



<J> = 35' 



Local 
Shear 



4 = k0° $ = 35' 



Estimated from 
Load Tests 



<t> = U0° Site A 



Site B 



1.0 815 2330 
1.5 1220 3500 
2.0 1630 U66O 



185 70U IU50 
277 1050 2100+ 
369 1^00 1800 



^250 
5300 
6000 + 



Note: calculated values from: 



q n , = 0.6 RN ; R = radius of 
ult y Y 



plate; y = 6l . 5 lb/ft 3 ; N from Terzaghi (19^3, p. 125) solution, 



TABLE 3. 

COEFFICIENTS OF SUBGRADE REACTION (TON/FT 3 ) 
CORRECTED TO 1 -FT PLATE (SITE B). (See correction note below.) 



Plate 

Dia. (D 

(ft) 



Site A Site B Proposed Values* 

q=l/2 ton/ft 2 q=l ton/ft 2 Loose Medium Dense 



1 
1.5 

2 
Avg. 



12 (?) 
86 
U3 
50 



Uo 


25 


80 


300 


111 


25 


80 


300 


177 


25 


80 


300 


110 


25 


80 


300 



^Terzaghi (1955) for submerged sands 



Correction = k n _, = k . x / 2D 
1 ft size 



Vl + D ) 



of those predicted by the Terzaghi equa- 
tion were obtained. 

One explanation for the higher 
bearing capacities is that the bearing 
capacity formula used here is actually 
a shortening of the following: 

q ult - 1/2T (2R) Vy 
As the "shape factor" s Y (~0.6 for a 



circle ) 


as suggest 


ed by 


Terzaghi (19^8) 


has been determine 


d empirically by com- 


par is on 


between circular 


and strip 


f oundat 


ions , Ny sh 
ane-strain" 


ould correspond to 


the "pi 


frict 


ion angle (for 


a strip 


footing ) , 


which 


is probably 2 


to 5 de 


grees higher than 


the triaxial 


friction angle (J. 


Brine 


h Hansen, 1966, 


writt en 


communi cat 


ion ) . 


According to 


more re 


fined calcu 


lations of N 



280 Marine-Geotechnique 

(Hansen, 1961, Figure l), the N y values of 0.5 ton per sq ft for site A and 

of 62 and 195 correspond to $ values of 1 ton per sq ft at site B. 
37.5 degrees and U 3 - 5 degrees, respec- 
tively. Tbrus , for site B, there is 

actually good agreement between a tri- FUTURE STUDIES 
axial angle of 38 degrees and a plane 
one of U3.5 degrees. As interest in placement of struc- 

In Figure 9, the ultimate bearing tures on the continental shelves in- 
capacities are plotted against the plate .creases, it will be necessary to develop 
diameters. On the basis of a buoyant a reliable in-place method to determine 
unit weight of 6l.5 lbs per cu ft, it the load-carrying behavior of shelf 
would appear that bearing capacity sediments. Only one approach is pre- 
factors N of 62 for site A and 195 for sented in this paper. There are two 
site B would be appropriate for use in major limitations to this procedure. 
Terzaghi's bearing capacity equation. First, conventional diving techniques 



limit the depth at which tests can be 
performed. Second, a special type of 
vessel and specially trained personnel 
must be used . 

Disallowing the possibility that 
tests up to 200 m or more water depth 
The relationship between the settle- might be made practicable by divers 



INFLUENCE OF DIAMETER OF LOADED AREA ON 
LOAD VS. SETTLEMENT BEHAVIOR 



ment an.d the plate diameter for site B is operating out of deep-submerged systems, 

shown in Figure 10 for loads of 1000 lbs per ^ f . rgt objection can be overco me by 

sq ft, 2000 lbs per s ft, U000 lbs per sq ft , automation and instrumentation of the 

and 6000 lbs per sqf.. Because the tests equipment described in this paper. A 

at site A were not performed in close hydraulic pump could be incorporated 

proximity, a similar analysis of these in thg load f rame ? and be cont rolled 

data was not undertaken. from thg surface . The preS sure in the 

Taylor (19U.8) postulated that the jack and the plate deflections could be 

settlement under a given pressure would raonitored electrically from the surface, 

be more or less independent of the size Th thg diver actlvit would be 

of the loaded area, falling off slightly tQ position the Jack and plate , set the 

as the size of the loaded area increased. -.,.,„+„„„-;„ j„fi„„+„„«4.„„ ^ „,,,• „„„ „„» 

electronic deflect omet er devices, and 

Such a relationship is shown m Figure survey the site. The vessel require- 

10. Terzaghi and Peck (19H8, p. ^26) ments could be subst ant ially simplifie d 

suggest the relationship by attaching floata tion chambers to the 

2 load frame and towing it to the test 

— *- = (— — — ) sites. It could then be sunk in position 

^1 and refloated by pumping out the 

floatation chambers, 
between settlement and the size of the Even the be st -des igned in-place 
loaded area. This relationship is also load tests will be expensive and 
plotted in Figure 10. The data from cumbersome. Therefore, the authors feel 
site B indicate that there is less that the development of a standard ship- 
settlement of the plate, under any load, board technique, such as the Standard 
as the diameter of the plate increases. Penetration Test used on land, is most 
This behavior pattern is consistent for desirable. The suggested device is a 
loads of 2000, U000, and 6000 1bs per sq ft. weighted penetrometer, built around a 
At 1000 lbs per sq ft, the settlement was convenient sampling device. This device 
almost identical for the 1.0-ft- and could record the depth of penetration, 
1 . 5-f t-diameter plates, but was consid- and possibly the resistance to penetra- 
erably less for the 2 . 0-ft -diamete r plate. tion versus depth, and obtain a disturbed 

Terzaghi (1955) has suggested values sediment sample. The representative 

of moduli of subgrade reaction (k) rep- grain-size distribution and degree of 

resentative of average values for sub- grain angularity of the sample could be 

merged sands. Values proposed by determined. The device should be 

Terzaghi are compared with those obtained calibrated in the laboratory first, and 

in this series of tests in Table 3. then in the field at sites of plate-load 

These values were corrected to a 1.0-ft- tests. Multiple regression analyses of 

diameter plate by the correction suggested the data could be undertaken and adequate 

by Terzaghi, and appear in Table 3. predictor equations relating ultimate 

Average values of 50 tons per cu ft and bearing capacity and load-settlement 

110 tons per cu ft for sites A and B, behavior to penetration, grain-size dis- 

respectively , were obtained under loads tribution, and grain angularity might be 




Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 281 

obtained. Thus, for certain rapid es- 
timates of the bearing capacity of 
surficial sandy sediments, all that 
would be required would be the data 
easily obtained by the penetr omet er- 
cor ing devi ce . 

CONCLUSIONS 

The most useful assessment of the Folk, R. L., and Ward, W. C. (1957 
load-carrying behavior of continental Brazos River bar: a study in the 
shelf sediments will be that gained by significance of grain size parameters, 
in-place load tests. Such tests generally Journal of Sedimentary Petrology , 
will be reliable because the sandy vol. 27, pp. 3-26. 
shelf sediments are relatively homo- 
geneous in the upper several meters. Hansen, J. B. (1961). A general 
However, load tests usually are so formula for bearing capacity, The 
cumbersome that a simply executed Danish Geotechnical Institute 
standard technique must be developed. Bulletin, 11, pp. 3 8 — U 6 . 

At the sites tested in this study, 

higher ultimate carrying capacities (1966). Improved 

were obtained than would have been pre- settlement calculation for sand. 

dieted by Terzaghi's bearing capacity The Danish Geotechnical Institute 

equation, based on the angle of shearing Bulletin, 20, pp. 15-20. 

resistance, <f> , of the soil. An analysis 

of load versus settlement behavior at Harrison, W., Lynch, M. P., and 

site B indicates less penetration under Altschaeffl, A. G. (I96U). Sediments 

less ultimate loading than would have of Lower Chesapeake Bay, with 

been expected from a conventional emphasis on mass properties, 

analysis (such as Terzaghi's pressure Journal of Sedimentary Petrology , 

versus width chart for 1-inch settlement). vol. 3U, pp. 727-755. 

In addition, the settlement under any 

given load decreased as the plate diam- Peck, R. B., Hanson, W. E., and 

eter increased. Thornburn, T. H. (1953). Foundation 



ACKNOWLEDGMENTS 



Engineering . New York, John Wiley 
& Sons. 1+10 pp. 



Shepard, F. P. (195 1 *). Nomenclature 

Commander Service Squadron 8, U.S. based on sand-silt-clay ratios, 

Navy, Norfolk, Virginia, made available Journal of Sedimentary Petrology , 

the USS Salvager (ARSD-3) for the field vol. 2U, pp. 151-158. 
tests. The Portsmouth Buoy Base, U.S. 

Coast Guard, Portsmouth, Va. , provided Silverman, M., and Whaley, R. C. (1952). 

the concrete buoy sinkers for the load Adaptation of the piston coring 

frame. The authors are grateful for device to shallow water sampling, 

the assistance rendered by the following: Journal of Sedimentary Petrology s 

Professor J. Brinch Hansen, The Danish vol. 22, pp. 11-16. 
Geotechnical Institute, Copenhagen, 

Denmark, for critically reading the Sowers, G. F. (1962). Shallow founda- 

paper; Mr. Earl W. Rayfield, Land and tions, Foundation Engineering , 

Sea Interaction Laboratory, Norfolk, Leonards, G. A., ed. New York, 

Va. , for helping in all phases of the McGraw-Hill Book Company, pp. 525-632. 
study; Capt. James Charles Rowland, 
Lt. E. E. McNiff, and Lt . J. C. Furr, 

U.S. Navy, for aid in designing the Sowers, G. F., Peck, W., and Gooding, P. 

load frame and guiding the field opera- (1966). Settlement of foundations 

tions aboard the Salvager; CPO H. R. on loose sand. Unpublished paper 

Carrol and CPO J. V. Kesser, U.S. Navy, given at the American Society of 

for directing the diving and coring work; Civil Engineers Structural Engineering 

and. Lt. E. E. McNiff, Lt . (j.g.) E. T. Conference, Miami Beach, Florida, 

Beckett, Ens. S. Kaye , and Messrs. January, 1966. 
D. R. Oney (EN2), N. L. R. Tetrault 

(HM2), B. S. Kepesky (BMCA), and J. D. Taylor, D. W. ( 19U8 ) . Fundamentals of 

Bitscheneider (DC2), U.S. Navy, for Soil Mechanics. New York, John 

making the dives. Wiley & Sons. 700 pp. 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 283 



Terzaghi, K. (19^3) . Theoretical Soil 
Mechanics . New York, John Wiley & 
Sons. 510 pp. 

(1955). Influence of 



geologic factors on the engineering 
properties of sediments, Economic 
Geology (50th Anniversary Volume), 
pp. 557-618. 



(1955). Evaluations of 



coefficients of subgrade reaction, 
G4otechnique t vol. 5, pp. 297-326. 

Terzaghi, K., and Peck, R. B. (19U8). 

Soil Mechanics in Engineering Practice 
New York, John Wiley & Sons. 566 pp. 



s 

<=> 

'6 



o 
■ — * o 

«-» If) 



uu 

CO 
CO 

Qi L 
Q- <=» 

CO 



o 



OH o 

LU O 

> ~ 
< 



s 



# 



# 



# 



WIDTH OF FOOTING (Feet) 
5 10 



1.0 



*. 



# SITE A 
+ SITE B 



41 







38< 



39' 



N=50 



N=40 



* 



36 



N=30 



N=20 




N=10 



N=5 



4.0 



WIDTH OF FOOTING (m) 



15 



o 

CO 



00 



g QC 

S co 

CO 
UJ 



o 
< 



8 



— s < 



Note : Diameter values from Peck, Hanson, and Thornburn , 1963, on 

basis of blow counts. 



FIGURE 1. PRESSURES AND WIDTHS OF FOOTINGS FOR 1-INCH SETTLEMENT ON SUBMERGED 

C0HESI0NLESS SOILS. 



284 Marine Geotechnique 



« SALVAGER ICLEVIS) 

PADS 
b CRANE PADS 
c SNUBBING PADS 
d JACKING PLATE 
e BARS 4"x'/2"x4'4" 
f I BEAM 10WF60 
g I BEAM 10WF33 
h 1 BEAM 6WF15 5 

CROSS BARS (On 
concrete blocks ) 




3V 8"- 
1,9.5* ta) 




:. . 



FIGURE 2. LOAD FRAME. TOP: DRAWING AND SPECIFICATIONS. BOTTOM: PHOTOGRAPH 
OF FRAME BEING TRANSFERRED - BY CRANE - FROM WHARF TO SUSPENSION 

CABLES OF USS SALVAGER. 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 285 



\WIVB. 



XWWWWWWX 10 ¥t J3\\\V 






FIGURE 3. SCHEMATIC REPRESENTATION OF TEST SETUP AND PHOTOGRAPHS OF COMPONENTS, 



286 Marine Geotechnique 




76° 13' 12' 

FIGURE 4. LOCATION OF TEST SITES. 



11' LONGITUDE 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 287 



100 



80 



O 



CO 



60 



oc 

uj 40 



U 

£ 20 



■■^^ '"-^ 
























\A3 












^~ 
















\ » \ A2 
















A1 \\B1 
NX 


k. 











E 
I 

h- 

a. 

LU 

a 



20 



40 



60 



80 



SITE A 



D r = 50 



D r = 67 



0.5 0.1 0.05 

GRAIN SIZE (mm) 

SOIL PROFILES 



0.01 0.005 



SITE B 



WELL SORTED 
SAND 



MODERATELY 
SORTED SAND 



POORLY SORTED 
CLAYEY SILT 



Or -57 



0.001 



WELL TO 
MODERATELY 
SORTED 
SAND 



TO 200 cm 



FIGURE 5. GRAIN-SIZE DISTRIBUTION CURVES AND SOIL PROFILES FOR SITES A AND B 



288 Marine Geotechnique 



Z 

o 



8.0- 

90 — 
10.0 — 
11.0 



AVERAGE PRESSURE ( lb/ft') 
.1,000 2.000 3.000 4 000 5.000 




- PLATE DIAMETER 



o 1.0 ft. (30.5cm) 
■ 1.5 ft. (45.7cm) 
a 2.0 ft. (61.0cm) 



J_ 



1 



5.000 10,000 15.000 20.000 

AVERAGE PRESSURE! kg /m') 



25.000 



FIGURE 6. LOAD VERSUS PENETRATION, SITE A. 



z 
o 

< 



9 3.0 



z 

LU 

a- 40 



AVERAGE PRESSURE (lb/ft 2 ) 
2,000 4JJ00 fiOOO 8,000 




PLATE DIAMETER 

o 1.0 ft. (30.5cm) 
s 1.5 ft. (45.7cm) 
a 2.0 ft. (61.0cm) 



10,000 20,000 30,000 40,000 

AVERAGE PRESSURE (kg/m 2 ) 



FIGURE 7. LOAD VERSUS PENETRATION, SITE B 



Plate-Load Tests on Sandy Marine Sediments, Lower Chesapeake Bay 



289 



b" 



50 



40 



30 



20 



10 



10,000 
— r 



20,000 
— i — 



((T, + C7 3 )/2kg/m2 
30,000 40,000 



50,000 



60,000 



TEST 
NO. 

1 
2 
3 



<p= 38° 

INITIAL 

VOID RATIO 

0.64 

066 

057 



FAILURE 

VOID RATIO 

0.67 

0.68 

0.59 




TEST NO. 3 



-X 

b" 

I 



90 



FIGURE 8. RESULTS OF DRAINED TRIAXIAL TESTS, SITE B [D = 0.55 (TEST 1); 

0.50 (TEST 2) : 0.72 (TEST 3)]. 



290 Marine Geotechnique 



fc 



< 

a. 

< 

U 

O 

z 

of 
< 



< 
2 






.2 




METERS 
.4 .6 .8 


6000 




i 




I V 1 



4000 


— 




G 


A— N y = 195 


2000 




7 






n 


— 




o, 

1 


*^N y =62 

1 



- 30,000 



20,000 

E 

H 10,000 



12 3 

PLATE DIAMETER (ft.) 

FIGURE 9. ULTIMATE BEARING CAPACITIES AND PLATE DIAMETERS AT SITES A AND B 



METERS 
.4 .6 



Q. 



1 i r~ 

P = SETTLEMENT UNDER GIVEN LOAD 

P, = SETTLEMENT OF l' DIAMETER PLATE UNDER 
SAME LOAD 



1- 



SITE B 




TAYLOR 



%$^'^0 ^ 



'*- - T -^rrrnr.4000 lb/ft' 



O 1 2 

PLATE DIAMETER (ft.) 

FIGURE 10. RELATIONSHIP OF SETTLEMENT AND PLATE DIAMETER AT SITE B 



19 



©This paper is published solely for the information of members of the 7th International Sedimenjolojlcal 
Congress and may not be reproduced, as a whole or in part, without the prior permission of the author. 

"PLEISTOCENE- RECENT BOUNDARY IN THE MALACCA STRAIT, SOUTHEAST ASIA 

G. H. Keller 
Institute for Oceanography, ESSA 

INTRODUCTION 

Several studies have been presented describing the Pleistocene drainage on the 
Sunda Shelf in the vicinity of Sumatra, Java and Borneo (Molengraaf f , G.A.F. 1919- 
Proc. Roy. Acad. Amsterdam. 23 , 395; Dlckerson, R.E. 1941. Univ. Pennsylvania . 
Bicentennial Conf ., Univ. Pennsylvania Press, Phila; Wyrtki, K. 1961. Naga Report , 2, 
Univ. Calif. Scrippslnst. Oceanography). Recent investigations to the north of this 
area in the Malacca Strait, reveal a marked change in direction of the Pleistocene 
drainage from that reported by the earlier studies of the shelf. Until now, little has 
been known of the depositional environment that existed on the Sunda Shelf during the 
Pleistocene epoch. However, an indication of the environmental conditions during the 
latter part of this epoch has been gained from the sediment cores collected during the 
investigations of the Malacca Strait. The following discussion presents the findings 
of these recent studies. 

The Malacca Strait Is a shallow passage between the Malay Peninsula and Sumatra 
connecting the Indian Ocean with the South China Sea. It is approximately 805 km long 
and varies in width from 64 km in the south to 257 km in the north. Water depths seldom 
exceed 45 m and more commonly are about 27m. Currents are generally strong, often reaching 
velocities of 2-1/2 knots in many areas. The strait is a part of the Sunda Shelf, which 
is one of the major continental shelf areas of the world. Unlike most others, this shelf 
is believed to be a peneplain formed in the late Pliocene (Molengraaf f, G.A.F. 1919. ibid). 

The area now occupied by the Malacca Strait was a topographic low in the peneplain prior 
to the Quaternary as a result of late Tertiary folding. This depression has been termed the 
"backdeep" as opposed to the foredeep presently located west of Sumatra (Bemmelan, R.W. Van, 
1949. The Geology of Indonesia , IA, Govt. Printing Office, The Hague). It was along this 
low that later regional runoff was channeled. 

During 1961 and 1964, oceanographic cruises by the U.S. Naval Oceanographic Office 
and the U.S. Coast and Geodetic Survey respectively, collected 76 sediment cores and 
conducted hydrographic surveys in the Malacca Strait. This study is based on these data. 

LOWERING OF SEA LEVEL 

As the Pleistocene icecaps grew, sea level was lowered and long periods of erosion 
followed. Stream and river channels were cut deeper and extended across the exposed 
continental shelf as a result of the lowering of their base-level. One Pleistocene river 
system to the north of Borneo, was approximately three times larger than that of the 
present Mississippi Rlver(Dickerson, R.E. 1941. ibid ). The lowering of sea level, estimated 
to be of the order of 73 to 91 m (Dickerson, R.E. 1941. Ibid ) resulted in an extensive area 
being laid dry and uniting the present islands of Sumatra, Borneo and Java with the 
Malay Peninsula. The extent of this exposed land area is approximated by the 80 m isobath 
(Fig. 1). 

It is generally accepted that the submergence of the Sunda Shelf was caused by the 
melting of the Pleistocene ice sheets rather than any by crustal movement (Molengraaf f ) 
G.A.F. 1921. Geographical Jour . 57 , 95 ; Bemmelan, R.W. Van 19^9, ibid) 



Ihe uniform depth of the shelf, between 55 and 64 m, and the numerous drowned river valleys 
tend to support this hypothesis. Carbon-l4 analysis of peat found in a sediment core taken from 
the strait at a depth of 26.5 m below sea level indicated an age of 10,000 ± 200 years 
B.P. (U.S. Geological Survey No. W-1675). This date agrees with similar dates on the 
curve established by Curray (i960. In Recent Sediments, Northwest Gulf of Mexico. 
Shepant, F.P, Phleger, F.B. , Andel, T.H. van (eds.). Sediments and history of the Holocene 
transgression, continental shelf northwest Gulf of Mexico , p 221) for the rise of sea level 
since the late Quaternary. It is evident from this correlation that the Malacca Strait has 
remained stable during the last 10,000 years. 

ERAINAGE PATTERN 

Further evidence of the Pleistocene-Recent history was found in other core samples 
as well as in the bathymetry of the strait. Previous discussions pertaining to the 
Pleistocene on the Sunda Shelf have usually dealt only with the drowned river channels 
extending eastward from southern Sumatra into the South China Sea (Molengraaff , G.A.F. 1921. 
ibid); Kuenen, Ph.H., 1950 Marine Geology , John Wiley and Sons, New York). As a result of 
the hydrographic data obtained from the recent oceanographic cruises the bathymetry of the 
strait can be delineated much more accurately than was possible in the past. A study of these 
data clearly reveals the presence of several drowned river channels extending from Sumatra and 
the Malay Peninsula into the Malacca Strait. These Pleistocene rivers comprised a major 
river system draining to the northwest into the Indian Ocean (Fig. l). No evidence is found 
to indicate that there was any major drainage to the southeast into the South China Sea. 
although this possibility should not be excluded without further study. 

Several completely buried channels, approximately 1 km wide and 9 to 10 m deep, have 
been observed on the echo-sounding records. Some channels are reflected in the present 
morphology of the strait floor which appear to have been even larger than those now 
completely buried. 

SEDIMENTS 

Approximately one-third of the cores taken in the strait penetrated what is believed 
to be the Pleistocene and exhibit two distinct layers: an upper layer of Recent sand with 
shell debris and an underlying Pleistocene stratum of stiff, gray, silty clay. The sand is 
characteristically dirty and composed of medium to fine sand-size particles of quartz, shell 
debris, glauconite and rock fragments. The underlying silty clay is homogenous and contains 
only minor or traceable amounts of shell and rock fragments. Peat is usually disseminated 
throughout the silty clay both as fine particles and as large fragments of wood or plant roots. 
The lower 15 cm of one core was entirely composed of peat. 

The pronounced change in sedimentary characteristics across this contact is quite 
evident (Figs. 2 and 3) . Texturally, the underlying silty clay is essentially uniform, but 
considerable compositional variations are found. 

A distinct Pleistocene-Recent boundary can be traced over large portions of the strait 
by means of the sediment cores and echo-sounding records because of the difference between the 
Recent and Pleistocene sediments mentioned above. This boundary commonly has an irregular 
profile - relief of 1 to 5 m - but often exhibits a flat surface. The Pleistocene sediments 
appear to crop out on the strait floor in many areas. The presence of Pleistocene submarine 
terraces similar to those described in the neighboring South China Sea by Krempf and Chevey 



(193^ Proc. Fifth Pac.Scl. Congress , 2, 849), were not observed in any of the echo-sounding 
records from the strait. If the terraces exist they are probably masked by Recent sediments. 

CONCLUSIONS 

The two sediment types found below the strait floor are indicative of two distinctly 
different environments of deposition. The silty clay has a relatively high organic and 
low calcium carbonate content corresponding to the relationship found in an estuarine 
environment (Emery, K.O., Stevenson, R.E. 1957- In Treatise Marine Ecology and Paleoecology, 
J.W. Hedgpeth (ed), v. 1, Estuaries and Lagoons , p. 673). The overlying coarse sediments 
represent the present high energy environment of the strait. I believe that the stiff clay 
represents a late Pleistocene estuarine deposit, which is in agreement with the Pleistocene 
geography proposed by Molengraaff (1921, ibid ) for this area. The stiffness of the clay 
indicates it may have been partially indurated as a result of sub-aerial exposure during 
a period prior to submergence. This clay was eroded during the period of exposure and the 
drainage pattern now observed in the present bottom topography is a result of that erosion. 
Based on the radiocarbon date mentioned earlier, from a peat sample taken 20 cm below the sand 
- sllty clay contact, it is reasonable to assume the stiff, silty clay is of late 
Pleistocene age. 

The depth of this Pleistocene surface below the present sea floor differs considerably, 
depending on the rates of deposition in the various portions of the strait. Sediment cores 
collected along the axis of the strait commonly penetrate this boundary at depths of 20 cm or 
less (Fig 3). However, in many areas cores 3 in In length do not penetrate to the Pleistocene. 
This may indicate a greater thickness of Recent sediment, or that the surface may have been 
obliterated by burrowing organisms such as seen in core W5 (Fig. 2). 

As sea level rose during the various interglacial periods and particularly at the end 
of the last glacial period, the rivers entering the strait were drowned and an estuarine 
environment evolved. This environment remained until the sea rose to a level submerging the 
entire Sunda Shelf. At this time the present strait environment came into existence. 

ILLUSTRIATIONS 

Fig. 1. Pleistocene drainage pattern. 

Fig. 2. Pleistocene - Recent contact as shown in sediment cores. 

Fig. 3- Vertical variation of textural and chemical properties in cores penetrating the 
Pleistocene sediments. 



100 200 



KILOMETERS 




BS-85 BS-96 



BS-II2 



fiq. 2 




i k, \ ijte 



STATION 
96 



Sand.Silt 
Clay 



.1, . , ,i. . . .i I L^J i 




Sorting 
1 2 3 



Ca Coq 

(%) 6 



Organic Carbon 



Nitrogen 



20 40 .4 .8 1.2 1.6 2.0 .04 .06 .08 

J_l l_J I ^J I L_l 1 I I I I I I I I I I 



i x 



RECENT 



/ / 



PLEISTOCENE iy 



T 
i 



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i 



STATION Md 

130 (0) 

3456789 10 



LU 




Or 


CtC 

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10- 


u 




20- 


z 


E 


30- 


X 




40- 


1— 






Q_ 
LU 




50- 


a 




60i 



I I I I I 



Sand 
Silt 
Clay 
(%) 100 



Sorting 


Ca Coo 


(0) 


234 


20 



1 

\ 




Organic 
Carbon 

(%) 
1.2 1.6 2.0 



Nitrogen 

(%) 
.05 .07 



i 

~T" 



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RECENT 
'JPLEISfOCENEY 



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fig. 3 



I SUBSAMPLE INTERVAL) 



Reprinted from THE JOURNAL OF SEDIMENTARY PETROLOGY Vol. 2>1 , No • 1 
Journal of Sedimentary Petrology, Vol. 37, No. 1, pp. 102-127 
Figs. 1-17, March, 1967 

The Society of Economic Paleontologists and Mineralogists 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 1 



20 



GEORGE H. KELLER 2 and ADRIAN F. RICHARDS 
Department of Geology, University of Illinois, Urbana, Illinois 



ABSTRACT 



The Malacca Strait is a shallow passage between the Malay Peninsula and Sumatra with oceanographic and 
bottom-sediment characteristics closely related to strong currents, debouching rivers, climatic variation, and 
the close proximity of bordering land masses. The strait assumed its present configuration as a result of the 
postglacial rise of sea level which drowned the Sunda Shelf. An essentially tidal northwest current flow prevail- 
ing in the strait throughout the year is largely responsible for the hydrographic and oceanographic conditions 
in the region. Surface salinities and temperatures are generally found to be lower than in the surrounding seas. 
A prominent wedge of cool-temperature, high-salinity bottom water is found to extend from the Andaman Sea 
into the strait. 

Bottom sediments primarily consist of muddy sands, with large areas cf mud occurring in the vicinity of 
river mouths and in the Andaman Sea. Calcium carbonate, primarily composed of mollusk shelL and fora- 
miniferal tests, and organic carbon are generally found only in minor amounts in the strait. Higher concentra- 
tions of calcium carbonate are confined to local shell deposits and larger percentages of organic matter are 
found in the vicinity of river mouths and in the fine sediments of the Andaman Sea. The non-calcareous detrital 
fraction is dominated by quartz with minor amounts of orthoclase and plagicclase feldspars. The heavy mineral 
suite is complex because of the varied geology of the bordering land areas and consists primarily of leucoxene, 
ilmenite, staurolite, biotite and amphiboles. Kaolinite and mixed-layer minerals consitute the dominant clay 
minerals; lesser amounts of illite and montmorillonite also are present. A slight decrease in illite and an increase 
in mixed-layer minerals with depth was observed in some cores. Volcanic ash of an andesitic origin is found 
throughout much of the area. Many cores penetrate what appears to be a Late Pleistocene surface consisting 
of stiff, slightly indurated silty clay. The clay contains much peat, some of which has given a radiocarbon date 
of 10,000 years B. P.; it appears to represent a former tidal flat or estuarine deposit. 



INTRODUCTION 

The Malacca Strait, a shallow passage be- 
tween the Malay Peninsula and Sumatra, con- 
nects the Indian Ocean with the South China 
Sea (fig. 1). It is approximately 805 km long and 
varies in width from 64 km in the south to 257 
km in the north. The strait provides a deposi- 
tional environment of considerable complexity 
owing to its physiography, oceanographic and 
climatological conditions, and the varied sedi- 
ment source areas provided by the adjacent land 
masses. This study was initiated to investigate 
the importance of these variables upon the sedi- 
ments of the strait. 

Previous studies were largely made to support 
fisheries research or as a minor portion of a more 
extensive study of the Sunda Shelf. The earliest 
recorded observations were those of the Dana 
Expedition between 1928 and 1930, from which 
plankton and oceanographic data were obtained 
from two stations in the strait. Surface salinity 
measurements over varying periods of time were 
reported by Soeriaatmadja (1956) and Selvara- 
jah (1962). Additional oceanographic stations 
were occupied by the Indonesian research vessel 

1 Manuscript received June 29, 1966. 

2 Present address: Institute for Oceanography, 
ESSA, Silver Spring, Maryland 20910. 



SAMUDERA (Anonymous, 1957) and the 
French vessel JEANNE D'ARC (Anonymous, 
1963). Wyrtki (1961) discussed the climatology 
and oceanography in the region of the strait as 
part of his study of the physical oceanography of 
the southeast Asia waters. Van Baren and Kiel 
(1950) include 18 samples from the strait in a 
sedimentary petrology study of the Sunda Shelf. 
According to the files of World Oceanographic 
Data Center A, five sediment samples were col- 
lected by the Russian Oceanographic vessel 
VITYAZ (cruise 35), but as yet these data are 
not available (B. S. Richmond, personal com- 
munication). 

In the spring of 1961, the U. S. Naval Oceano- 
graphic Office began an investigation of the 
general sediment distribution and hydrographic 
conditions within the Malacca Strait; a more de- 
tailed survey and sampling program was under- 
taken later in 1961. During March and April 
1964, the senior author, while aboard the U. S. 
Coast and Geodetic Survey Research Vessel 
PIONEER, obtained additional hydrographic 
data as well as bottom samples to supplement 
those collected by the Naval Oceanographic Office. 
Data collected during these three cruises include 
observations obtained from 24 oceanographic 
stations (temperature and salinity), 155 bottom 
sediment stations, and five 26- to 33-hour anchor 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



103 



stations for the determination of the spatial and 
temporal variations of currents (fig. 2). It is up- 
on these data that this study is based. The loca- 
tions of all stations plus the sedimentological and 
oceanographic data obtained at each site are on 
file at the National Oceanographic Data Center, 
Washington, D. C. (NODC geology acquisition 
number 051866-1 and cruise numbers 00545 and 
00639). 

PHYSIOGRAPHY AND AREAL GEOLOGY 

Bordering Lands and Islands 
The regional physiography and geology of the 
adjacent lands is germane to this investigation 
because sediments brought to the strait are con- 
trolled by the nature of these bordering pro- 
vinces, as will be demonstrated later. 

Sumatra can be divided topographically into 
three parallel provinces extending along the is- 
land from northwest to southeast; the Barisan 
Mountains, a transition zone, and a wide coastal 
plain. The volcanic Barisan Mountain chain 
largely consists of Late Paleozoic crystalline 
schists with some shallow depressions containing 
Mesozoic, Tertiary and Quaternary sediments. 
Tertiary-Quaternary volcanics, including rhyo- 
lite and pumice tuffs as well as andesite cones, 
cover wide portions of the province. Some iso- 



lated intrusives of plutonic rock of possible 
Quaternary age constitute the remaining out- 
crops (fig. 2). The mountains descend gradually 
eastward to a transition zone of rolling hills com- 
posed of Paleozoic schists and Mesozoic and 
Tertiary sediments. Minor amounts of Tertiary- 
Quaternary rhyolithic tuff and plutonic intru- 
sions also occur in the transition zone. The third 
zone is an extensive flat lowland of Quaternary 
and Recent sediments that borders the strait; it 
is 48 to 193 km wide. Most of this coastal zone is 
swampy and covered by jungle. Although nu- 
merous rivers drain both sides of Sumatra, the 
majority have their headwaters in the Barisan 
Mountains and drain into the strait. The east 
coast of Sumatra has generally shifted consider- 
ably toward the strait owing to the deposition of 
the large sediment load of these streams (Van 
Bemmelen, 1949, p. 702). A recent mariner's re- 
port based on actual observations compared with 
existing charts for the area by H. P. Hansen 
(personal communication) indicates, however, 
that the shoreline along northeastern Sumatra in 
the vicinity of Belawan has receded as much as 2 
km. Hansen has also observed drowned tree 
stumps 300 m off shore in this same area. 

The Malay Peninsula consists of a hilly and 
mountainous interior bordered on both sides by 



100 



110 



120 




10 







10 



CO ^ 



10" 



o u 



10 C 



100 110" 120^ 

Fig. 1. — -Index map, Malacca Strait and adjacent seas. 



104 



GEORGE II. KELLER AND ADRIAN F. RICHARDS 




96 9 8 100 102 104 106 

Fig. 2. — General geology of the bordering land areas and station locations in the Malacca Strait. 



coastal lowlands. Several north-south trending 
mountain ranges extend from the Thailand bor- 
der across approximately two-thirds of the pen- 
insula, becoming discontinuous in the southern 
third. Granitic intrusives of Jurassic age crop out 
along the entire length of these ranges as well as 
in the south, where little of the high relief re- 
mains. A. hilly topography exists between the 
ranges, which consists mainly of Permo-Carbonif- 
erous limestones and shales and Triassic arenace- 
ous deposits (Van Bemmelen, 1949, p. 360). 
Effusive rocks of unknown composition are 
common throughout much of this region. Rolling 
hills and lowland plains of Paleozoic and Qua- 
ternary sediments extend out from the moun- 
tains toward the coast where the coastal low- 
lands bordering the strait have an average 
width of 64 km. The extensive volcanism that 
occurred on Sumatra in the Quaternary also re- 
sulted in the widely distributed ash deposits on 
the Malay Peninsula (United Nations Economic 
Commission for Asia and the Far East, 1961, p. 
36). 

The islands in the vicinity of Singapore consist 
mainly of sedimentary rocks and granites of 
Mesozoic age. To the north, Penang Island is also 
composed of Mesozoic granites, and Langkawi 
Island near the border of Thailand consists pre- 
dominantly of an Ordovician-Silurian calcareous 



sequence (Alexander, 1959). Islands along the 
coast of Sumatra in the narrow portion of the 
strait are formed of Recent sediments. 

Determination of the sedimentary provenance 
in the strait is difficult as a result of the numer- 
ous streams and rivers draining the complex and 
varied geology of the adjacent lands. Sumatra 
has the greatest influence on the sediments of the 
Malacca Strait although Malayan drainage con- 
tributes large quantities of material. Much of the 
sediment entering the strait from Sumatra ap- 
pears to be finer than that from streams drain- 
ing the Malay Peninsula. This is attributed to 
the extensive drainage system from western 
Sumatra eastward across the lowlands and fi- 
nally through the wide coastal plains covered with 
thick vegetation. There is a tendency in the 
coastal region for much of the coarser part of the 
sediment load, that otherwise reaches the strait, 
to be intercepted. Islands south of Singapore 
contribute only minor amounts of material to 
the southern portion of the strait, as indicated by 
the concentration of various iron minerals be- 
lieved to have come from the laterite deposits 
on these islands. Wind-derived sediment is 
present in the form of volcanic ash and pumice, 
but it is of minor importance relative to the 
quantity of stream-borne material. Much of the 
ash found in the strait is considered to be detri- 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



105 



tal rather than wind-borne. Sediment entering 
from the Andaman Sea consists mainly of plank- 
tonic foraminifera carried in by southeast-flow- 
ing bottom currents. Organic production in the 
strait is the only remaining source of sediment, 
and in some regions it is a significant source. 

Strait Floor 

The topography of the strait floor prior to 
1961 was only generally known because of the 
lack of adequate bathymetric surveys. Data from 
the recent cruises of the Naval Oceanographic 
Office and the Coast and Geodetic Survey have 
provided much more detail. Contours at 10 
fathom (18.3 m) intervals in the strait and 100 
fathom (183 m) intervals beyond the continental 
shelf have been drawn (fig. 3) based on these re- 
cent soundings that are corrected for sound 
velocity and those from the U. S. Hydrographic 
Office Chart 1595 that are mainly wire-line 
soundings. 

Numerous islands clutter the southern en- 
trance to the strait where water depths seldom 



exceed 20 fathoms (37 m) and more commonly 
are about 15 fathoms (27 m). Within the narrow 
portion of the strait, from Singapore northwest- 
ward to approximately Port Swettenham, water 
depths increase slightly toward the middle por- 
tion with shallower sill-like depths at both ends. 
The shallow areas that occur at either end may 
be due to relict deposits which are expressions of 
the topography prior to an eustatic rise of sea 
level. 

The broad shallow areas bordering Sumatra 
along the southern portion of the strait result 
from the large quantity of sediment supplied by 
local rivers. In this region, prominent fine sand 
and mud ridges trend parallel to the axis of the 
strait. Some of these ridges rise as much as 21.9 
m above the bottom and are up to 48 km long 
(fig. 4, profiles A & B). Present orientation of 
these ridges appears to be maintained by bottom 
currents, which may reach velocities of 77 to 103 
cm/sec. Umbgrove (1949, p. 5) reports the pres- 
ence of similar features to the south in Banka 
Strait, between Sumatra and Banka Island, 




Fig. 3. — Bathymetry of the Malacca Strait with a 10-fathom (18.3 m) contour interval from 
10 to 100 fathoms and a 100-fathom (183 m) interval beyond 100 fathoms. 



106 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 







«2 40 
E 80 
9 120 
i3 160 
,« 200 
240- 




vert X100 



Fig. 4. — Depth profiles. 



which he describes as remanent features result- 
ing from currents eroding numerous channels in 
the floor of the strait and leaving ridges between 
the channels. The term "channel," as used by 
Umbgrove is a misnomer in that the bathymetry 
shows no indication of trenches or channels hav- 
ing been cut in the strait floor. Ridges occur 
above the sea floor in the Malacca Strait and the 
depressions one commonly associates with chan- 
nels are not found. If these ridges are the result 
of erosion by sea currents, as Umbgrove (1949, 
p. 6) suggests, one would expect the ridge tops 
to be at the same depth as the floor of the strait 
surrounding the area where these features are 
found. This is not the case. We believe the ridges 
in both straits are depositional rather than ero- 
sional features. Once the sediments from the 
Kampar River and its tributaries enter the strait 
they are carried northwestward by the currents. 
Farther out in the strait some of these sediments 
are deposited to form linear ridges parallel to the 
current flow and extending away from the river 
mouths. Some ridges show a gradual tapering in 
width away from the rivers. Many of the ridge 



tops are composed of mud, but sand is generally 
found in the troughs. Shepard, Emery, and 
Gould (1949, p. 28) suggested that the presence 
of sand between the ridges may possibly be 
attributed to erosion of the ridges. Since the 
ridges result from the deposition of fine sedi- 
ments entering the strait from nearby rivers, the 
possibility that enough sand would be available 
from erosion of the ridges seems doubtful. It is 
more likely that the sand is transported into the 
area (and concentrated in the troughs) by cur- 
rents moving through the strait. Van Veen 
(1936, p. 198) believes that these features are 
similar to the sand ridges he has observed in the 
Straits of Dover. The only similarity between the 
ridges in these two areas is that they are deposi- 
tional features formed parallel to the current 
flow. The ridges in the Strait of Dover are at- 
tributed to strong currents and a small supply of 
sand, whereas those in the Malacca Strait are 
the result of strong currents and large quantities 
of fine sediment. 

The general physiography of the strait floor 
was probably established during a period of 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



107 



lower sea level in the Late Pleistocene. Present 
sea currents tend to maintain the bottom con- 
figuration except in areas where large quantities 
of sediment are deposited from nearby rivers 
such as in the southern portion of the strait. 

Sand waves occur in the region consisting en- 
tirely of coarse to medium sand in the area of 
maximum current velocity between Malacca 
and Port Swettenham. These waves are oriented 
perpendicular to the axis of the strait and have 
wave lengths of approximately 241 to 900 m and 
heights of 4.6 to 15.3 m (fig. 5). The larger waves 
show a definite asymmetry with steep slopes to 
the northwest. Smaller waves tend to show a 
greater degree of symmetry. Small sand waves 
also occur near One Fathom Bank, west of Port 
Swettenham (Wyrtki, 1961, p. 9). 

In the central portion of the strait (lat. 4° 42' 
N., Long. 99° 07' E), underwater photographs 
revealed the presence of small ripple marks 
having heights of 3 to 4 cm that trend in a north- 
west-southeast direction. This unusual trend, 
parallel to the general current flow, is attributed 
to local variation in current direction. 

The strait widens to the northwest from a 
width of 64 km at Port Swettenham to about 257 
km where it enters the Andaman Sea. Over this 
distance the axis of the strait gradually deepens 
(fig. 4, profile E). The slope off the coast of the 



Malayan Peninsula decreases to the north, but 
increases along the Sumatra coast (fig. 4, pro- 
files C and D). The 50 fathom (91.4 m) "hole" 
west of Port Swettenham may be a relict feature 
of Pleistocene drainage or possibly structurally 
controlled. Little can be said about the latter 
possibility without subbottom information. The 
presence of Pleistocene submarine terraces, 
similar to those found in the neighboring South 
China Sea (Krempf and Chevey, 1934, p. 849), 
were not observed in any of the echo-sounding 
records from the strait. If present, they may 
have been masked by Recent sediments. Bottom 
contours indicate the presence of a drowned 
river channel extending northward from the 
mouth of the Rokan River. Numerous sub- 
merged river valleys have been reported and de- 
scribed on the Sunda Shelf by Molengraaff 
(1921), Umbgrove (1949, p. 2), and Kuenen 
(1950, p. 482). 

DEPOSITIONAL ENVIRONMENT 

Climate 
Climatological variation directly influences 
depositional conditions in the strait in two 
major ways: runoff from bordering land prov- 
inces and general circulation in the strait. Since 
both factors are significant to an understanding 
of the sediments in the Malacca Strait a brief 




1 f •^W^WW^\b T^p^f 



-90 



400- 
(ft) 







km 



-120 
(m) 



Fig. 5. — Sand waves. Series of nearly continuous echo-sounding records taken from an area 
extending south-east from Port Swettenham. 



108 



GEORGE II. KELLER AND ADRIAN F. RICHARDS 



96 98' 



100 102 104 9 6 9 8 



SURFACE 
CURRENTS&WINDS 

(n.e. monsoon) - 



10 20 

i , , , 1 1 

wind°/ 9 _ 




100 102 104 



96" 98 v 



100 102 104 




10 



— i 1 

SURFACE 
CURRENTS&WINDS 
(s.w. monsoon) Jq 



10 20 

i .... i , ... i 

wind % - 



96 98 



100 102 104 



Fig. 6. — Surface currents and winds during the northeast and southwest monsoons. Wind roses fly with the 
wind, and the number of barbs on the arrow indicate the Beaufort scale of average wind force. The length of 
the arrow measured from the center of the circle gives the average percent of time the wind blows in a particular 
direction. The number in the circle indicates the percent time of calms. Modified from the U. S. Navy Hydro- 
graphic Office (1944). 



discussion of the climatological aspects is per- 
tinent. The climate of the region is typically 
equatorial — hot and humid. Monsoonal effects 
are not as severe in the strait as in the more open 
surrounding seas because of the sheltering effect 
offered by the Malay Peninsula and the island of 
Sumatra. Indirectly, however, the monsoon 
seasons greatly influence the circulation in the 
strait. As a result of the monsoons, two rainy 
seasons of unequal magnitude occur without any 
really dry period. Average annual rainfall over 
most of the area ranges from 1961 to 2649 mm, 
with the greater rainfall occurring in the lower 
latitudes (U. S. Navy Hydrographic Office, 
1951, p. 18). 

Variation in surface wind direction and force 
follow the monsoonal seasons. Northeast mon- 
soon conditions prevail from December to 
March. Near the equator during this time the 
variable winds have an average Beaufort force of 
2 or 3 and originate mainly from the north. The 
southwest monsoon season extends from May to 
October and is preceded by squally weather, 
strong winds and considerable rain. Winds are 
mainly from the south and southwest and are of 
about the same force as those occurring during 
the northeast monsoon (Royal Netherlands 
Meteorological Institute, 1935). Severe squalls 
with gale force winds often accompany the 
southwest monsoon, but have little influence on 
the circulation in the strait because of their 



limited fetch (Great Britain Hydrographic De- 
partment, 1958, p. 31). Wind roses and the 
associated surface currents for the two monsoon 
seasons are shown in figure 6. 

Oceanography 

An understanding of tides, currents, salinity 
and water temperature is important in the 
interpretation of a shallow-water marine sedi- 
mentary environment. Currents normally ac- 
count for the grain-size distribution. Tempera- 
ture and salinity measurements delineate various 
water masses, which usually have considerable 
influence on the type of sediments deposited, 
particularly those of organic origin that are de- 
pendent on the properties of the overlying water. 

Oceanographic conditions in the Malacca 
Strait differ considerably from those of the sur- 
rounding seas yet they are greatly influenced by 
the currents and water masses driven into the 
strait fr ; om these seas by the monsoons. The 
most significant effect of the monsoons is their 
regulation of the circulation in the South China 
and Java Seas as well as the Indian Ocean, which 
in turn control conditions in the strait. Within 
the strait only a minor effect is noted directly 
from the monsoons because of the shielding pro- 
vided by the bordering land masses. Heavy 
rainfall in the higher elevations of the bordering 
lands, however, results in a large runoff into the 
strait which does influence salinity conditions. 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



109 



Tides and Currents. — Currents flow through the 
strait in a general northwest direction through- 
out the year as a result of monsoonal effects on 
the neighboring seas. This flow is also strongly 
influenced by tides. It is a continuation of the 
south-flowing current during the northeast mon- 
soon which rounds the tip of the Malay Penin- 
sula from the South China Sea and passes into 
the strait (fig. 6). During the southwest mon- 
soon, part of the northwestward-flowing water 
moving from the Java Sea into the South China 
Sea passes directly into the Malacca Strait 
(U. S. Navy Hydrographic Office, 1945). Cur- 
rents are weak in June, July and August, and 
often a southeast flow is recorded as a result of 
the Indian Ocean current pattern that causes a 
pile up of water in the Andaman Sea. The differ- 
ence in sea level during this period from the 
southern to the northern entrance of the strait is 
of the order of 10 to 15 cm with the slope toward 
the Andaman Sea. At the time of maximum flow 
to the northwest in January to March a differ- 
ence in sea level of 50 cm has been reported by 
Wyrtki (1961, p. 126). Measurements during 
similar periods on both sides of the strait at vari- 
ous points indicate that there is little if any 
difference in sea level across the strait (Wyrtki, 
1961, p. 125). 

Tides are of the semidiurnal type throughout 
the strait except in the southern portion near 
Singapore where they are of a "mixed type." 
Flood currents set to the southeast and ebb to 
the northwest in the strait. The combination of 
tide and the general northwesterly flow causes 
the ebb to last longer and run slightly stronger 
than the flood. Current velocities average be- 
tween 55 and 103 cm/sec. in the center of the 
strait, but closer to shore and in restricted chan- 
nels they may reach 180 cm/sec. during spring 
tides. 



Five current stations were occupied for periods 
of 26 to 33 hours during November 1961 (fig. 2). 
All measurements were made with a Roberts 
current meter. Surface and bottom currents for 
four of these stations as well as the respective 
tides are shown in figure 7. Tidal conditions at 
stations A and B are more uniform and the 
curves show less inequality than at stations C 
and D, which would be anticipated in an area of 
semidiurnal tides. North of Penang Island at 
station B, bottom currents are of about the 
same or slightly higher velocity than surface 
currents during times of flood, but appear to be 
slower during ebb (fig. 7). Bottom currents tend 
to be stronger than surface currents during 
periods of flood along the western margin of the 
strait at station A. The general surface current 
pattern during the southwest monsoon indicates 
that currents turn away from the vicinity of 
Penang Island and flow westward toward Suma- 
tra (fig. 6). This is believed to account for the 
slightly higher current velocities observed near 
Sumatra at station A. Tidal currents are com- 
plex in the narrow part of the strait, particularly 
just north of Singapore. At station C, between 
the Kampar River mouth and Singapore, sur- 
face currents flowing towards the northwest are 
strongest during ebb flow while bottom currents 
in the opposite direction are strongest during 
flood. A surface velocity of 108 cm/sec. at station 
C was the highest measured in the strait during 
this series of current observations. Station D, 
southeast of Singapore, is in an area affected by 
tides from both the Malacca Strait and the 
South China Sea. Surface and bottom currents 
at this station have essentially the same velocity. 
These currents are variable in direction and 
little information can be gained from this single 
station when compared with the local tide data. 

Sediments within the strait are predominantly 



CURRENT 
N W 

(knots) 



CURRENT 

NW I SE 

(knots) 

a O 




Fig. 7. — Tide and current observations from various portions of the Malacca Strait. 
The locations of stations A to D are shown in figure 2. 



110 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 



transported to the northwest, because of the 
general current pattern. This is particularly 
evident in the narrow portion of the strait be- 
tween Malacca and Port Swettenham where the 
steep slopes of the large asymmetrical sand 
waves are inclined to the northwest. Local varia- 
tions in currents and bottom topography in the 
northern and central parts of the strait also ac- 
count for the movement of sediment in directions 
other than to the northwest as indicated by the 
small ripple marks mentioned earlier. The rela- 
tively short period of current observations pre- 
sented here gives only an indication of the gen- 
eral current conditions with depth during the 
beginning of the northeast monsoon. Longer and 
more frequent observations are required to 
interpret more adequately the current-sediment 
relationship. While the above-mentioned cur- 
rents are of great importance in transporting 
sediment throughout much of the strait, streams 
draining the adjacent land areas are also signifi- 
cant with respect to sediment distribution along 
the coastal margins. Stream currents in these re- 
gions appear to be stronger than the currents in 
the strait and account for much of the sediment 
transported into these areas. 

Salinity. — A south-flowing current rounds the 
Malay Peninsula from the South China Sea and 
causes water of salinity greater than 32.0% 
to enter the Malacca Strait, displacing the low 
salinity waters in the southern portion of the 
strait during the northeast monsoon (Soeriaat- 
madja, 1956, p. 31). This low salinity water 
moves northward mixing with the higher salinity 
water of the central and northern portions of the 
strait. The result of this movement is a salinity 
maximum in the southern part of the strait dur- 
ing the northeast monsoon in spite of the heavy 
rainfall. 

A decrease in salinity in the southern portion 
of the strait is thought to be caused by runoff 
from the large rivers on the east coast of Suma- 
tra and the low salinity water entering from the 
Java Sea during the southwest monsoon (Sel- 
varajah, 1962, p. 2). The annual variation of sur- 
face salinities in the northern and central parts 
of the strait shows two maxima and two minima, 
essentially a mirror image of the amount of rain- 
fall (Soeriaatmadja, 1956, p. 30). Rainfall and 
salinity are not interdependent factors to the 
south. 

Surface salinity measurements made during 
late March and early April 1961 do not agree 
with the general pattern described by Soeriaat- 
madja (1956, p. 40) for that time of the year. 
Soeriaatmadja shows an almost uniform surface 
salinity throughout the eastern half of the strait 
and lower salinities along much of the Sumatra 



coast. Data used in the present investigation 
indicate an increase in salinity from Port Swet- 
tenham to the Andaman Sea and a distribution 
pattern clearly reflecting the general current flow 
to the northwest. Additional measurements ob- 
tained by the Research Vessel JEANNE D'ARC 
during late March 1963 (Anonymous, 1963) are 
in concurrence with the pattern shown in figure 
8. The salinity distribution pattern shown by 
Soeriaatmadja (1956) represents an averaging of 
data over a five year period which may account 
for the discrepancy mentioned here. The pattern 
of bottom salinity shows an even more pro- 
nounced high salinity wedge extending south- 
eastward into the strait. This wedge is more 
evenly distributed across the strait at depth than 
at the surface. The bottom currents flowing to 
the southeast during periods of flood may help to 
maintain the position of this wedge. Salinity 
profiles also show this wedge to be thicker along 
the western margin of the strait and sloping to- 
wards the east (fig. 9). The penetration of higher 
salinity water from both the Indian Ocean and 
the South China Sea is readily apparent in the 
axial profile. The influence of large rivers is also 
clearly evident from the profiles and areal pat- 
terns, particularly in the southern entrance to 
the strait. Within the narrow, shallow part of the 
strait very little variation is found both laterally 
and vertically as a result of mixing. 

Temperature. — The average annual variation of 
sea surface temperature is approximately 1.5° C. 
and is closely related to changes in the air tem- 
perature (Wyrtki, 1957, p. 21). Measurements 
made during March and April 1961, indicate 
that surface temperatures increase from off the 
Sumatra coast northeastward across the strait 
(fig. 8). This gradient, transverse to the axis of 
the strait, probably results from less mixing and 
weaker currents along the eastern margin of the 
strait. 

Bottom temperature measurements during 
this same period show a cooler wedge of water 
extending into the Malacca Strait from the 
Andaman Sea and a general increase in tempera- 
ture to the southeast. Isothermal conditions 
exist in the narrow portion of the strait because 
of vertical mixing. 

Temperature profiles across the strait show a 
distinct tongue of warmer water along the east- 
ern margin of the strait. The southeastward ex- 
tension of cooler Indian Ocean water along the 
bottom is clearly shown in the axial profile (fig. 
9). 

An important influence on the sedimentary 
environemnt of the north and central portions of 
the strait is the large wedge of cool, high salinity 
water that extends into the area from the Anda- 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 111 



9 6° 98° 100° 102° 104° 9 6° 98° 100° 102° 104° 




96 98 100 102 104 96 98 100 102 104 

Fig. 8. — Water temperature and salinity distribution for April 1961. 




STATIONS 214 24 20 

^40- ---' 
o- 2 60- -34 

LU D 

Q £ 80 

~100 

A A 

STATIONS 2 5 24 23 

20- 

Q-«j 60- 

Luaj - ~" 3 <0-. 

QE 80- 

~100- 



SALINITY 

(%o) 



TEMPERATURE 

(°C) 



200 

— I 



Fig. 9. — Water temperature and salinity sections. 



112 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 



man Sea. We believe this wedge is more or less 
stationary and is not an actively moving water 
mass. The fluctuation of bottom currents with 
changes in the tide is probably largely responsi- 
ble for the location of this wedge. The signifi- 
cance of this water mass with respect to the 
sedimentary constituents is discussed in a later 
section. 

Sediments 

The complexity of the depositional environ- 
ment in the Malacca Strait is mainly attributed 
to the varied sediment source areas provided by 
the bordering land provinces and to the oceano- 
graphic conditions in and around the strait. 
Tectonic activity in the adjacent land masses 
has resulted in extensive areas of igneous in- 
trusion and associated zones of metamorphic 
rock which contribute numerous mineral suites 
to the rivers entering both sides of the strait. In 
addition, the remains of both planktonic and 
benthonic faunas are found in the bottom sedi- 
ments. Factors other than source material tend 
to further complicate the environment. The 
magnitude of river discharge increases con- 
siderably during the winter and summer months 
as the result of monsoonal rains. Sediment enter- 
ing the strait is subjected to a strong annual 
northwest current that has superimposed upon it 
a semidiurnal tidal current having a flow of 
nearly 55 cm/sec. to the southeast, then later 
reverses direction to flow northwest at velocities 
up to 100 cm/sec. Bottom irregularities account 
for isolated patches of coarse or fine material 
within areas of nearly uniform sediment type. As 
a result of these many factors constituting the 
depositional environment, the various sediment 
parameters of size, sorting, mineral content and 
other constituents undergo short term spatial 
and temporal variations of considerable magni- 
tude. 

One hundred-forty-one grab samples and 76 
sediment cores were collected at 155 stations 
(fig. 2). An orange-peel bucket sampler (Sumner, 
and others, 1914, p. 7) and the Shipek grab 
sampler (manufactured by Hydro Products, San 
Diego, California) were used to obtain the sur- 
face samples. All cores with the exceptions of 
those at stations 184, 185, 195, 199, 202, 204 and 
209 were collected with a Phleger corer (U. S. 
Hydrographic Office, 1955, p. 54-57), and the 
remainder was taken with a modified Hydro- 
plastic corer using a piston (Richards and Keller, 
1961). Core lengths vary from 10 to 349cm, 
averaging about 46 cm. Only relatively short 
cores were obtained from much of the area be- 
cause of the coarse surface sediment and an 
underlying stiff clay. 

Cores taken in the vicinity of large rivers indi- 



cate that the thickness of silt and lutite extends 
throughout the sampled interval, while farther 
away from the rivers sand overlies finer sedi- 
ments. Sediment grain size and calcium car- 
bonate content vary considerably with depth 
from station to station. In some areas only 
minor variations of the sedimentary parameters 
are noted with depth, while in others a pro- 
nounced change is seen where the core pene- 
trates a prominent silty clay layer. The influence 
of local conditions is clearly evident from the 
sediment cores. 

Textures 

Prior to this investigation the only available 
textural information on the bottom sediments in 
the Malacca Strait came from chart notations 
which were based on brief visual examinations of 
sediment adhering to the tallowed lead used in 
early hydrographic surveys. The validity of 
many of the notations is questionable because of 
the manner in which samples were collected and 
the crude field descriptions usually logged by 
mariners. Shepard, Emery, and Gould (1949) 
compiled these notations into a series of sedi- 
ment distribution charts for the east Asiatic 
shelf areas. Their study of the Malacca Strait 
shows that along the axis the bottom is com- 
posed mainly of firm sand and mud and irregular 
patches of sand and rock. Mud was found to 
predominate in the north-central and north- 
eastern sections of the strait. 

Based on the surface distribution of various 
textural parameters determined during this in- 
vestigation, the depositional environment of the 
Malacca Strait can be divided into four distinct 
regions (fig. 10), if local irregularities are ignored: 
north of Penang Island (Northern); Penang 
Island to Port Swettenham (Central); Port 
Swettenham to Malacca ("Narrows"); and 
Malacca to Singapore (Southern). 

Sediment samples are assigned to one of four 
types based on grain-size analysis data: sand (at 
least 90 percent of the sample consisting of mate- 
rial coarser than 4 phi); muddy sand (50 to 90 
percent sand grains); sandy mud (10 to 50 per- 
cent sand) ; and mud (at least 90 percent consists 
of material finer than 4 phi). While the distri- 
bution of these textures shows a vague agree- 
ment with the bottom notations mentioned 
above, the more detailed classification used here 
affords a better delineation of the sediment 
types. Mud deposits are less extensive than indi- 
cated by Shepard, Emery, and Gould (1949), 
particularly in the Northern region; they are 
found mainly in the vicinity of river mouths and 
in the Andaman Basin. The present study finds 
that muddy sand is the dominant sediment type 
in the strait. Sand occurs throughout large 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



113 



areas, but mainly in association with gravel and 
large shell fragments along the axis of the strait 
as well as along the continental shelf break where 
currents tend to winnow out the finer material 
(fig. 11). An attempt was made to verify the 
presence of rock areas reported by Shepard, 
Emery, and Gould (1949), but none were found. 
Vertical variation of the textural properties 
appears to be minor. Most cores penetrating 
only the Recent surface sediments show little 
variation whereas those reaching the underlying 
stiff clay reveal a distinct change in textural 
properties. Grain size decreases markedly and 
sorting generally is poorer below this contact. 
Within the clay the properties again are re- 
markably uniform. A 3.84 m core from the 
southern portion of the Andaman Basin shows 
little change in the textural parameters with 
depth. 

Color. — Color of the grab samples was deter- 
mined at the time of their collection by com- 
parison with the Rock-Color Chart devised by 
Goddard, et al., (1948). Color determination of 
the wet core samples was made later in the 
laboratory. Nearly all samples can be approxi- 
mated by five main colors if minor transitions 
are ignored: grayish olive (10Y4/2), olive gray 
(5Y3/2), light olive gray (5Y5/2), dusky yellow 
green (5GY5/2), and medium gray (N5). Sedi- 
ment colors often indicate different depositional 
environments and are commonly related to such 



parameters as grain size, sorting, or carbonate 
content (Niino and Emery, 1961, p. 749). This 
relationship does not appear to hold true for the 
Malacca Strait. The grayish-olive material 
found over much of the Central and Northern 
regions includes sediments varying in texture 
from mud to sand. This variation of texture is 
also true for the other colors. It appears that in 
the Malacca Strait sediment color is not signifi- 
cantly indicative of the conditions in the de- 
positional environment, but rather of the source 
areas from which the sediments are derived. Al- 
though there is a lack of samples from the vicin- 
ity of river mouths, there is a strong indication 
that the observed color patterns are related to 
the sediments coming from the rivers (fig. 11). 
Each area delineated by a different color is 
found to be associated with one or more streams. 
An indication of this relationship is noted in 
samples collected off the mouth of one river in 
the southern portion of the strait, where the 
freshly collected river sediment has the same 
color as that found further away from shore. 

The large extent of grayish-olive material 
across the northern portion of the strait is prob- 
ably related to the current system in the area. 
Examination of samples from north of the strait 
and in the Andaman Sea appears to indicate a 
less complex pattern as one might expect where 
local drainage is not significant. 

Median Diameter. — Grain-size analyses were 



CLAY 




REGIONS OF THE STRAIT 

x NORTHERN 
o CENTRAL 
A "NARROWS" 
• SOUTHERN 



SAND 7 5 50 



SILT 



5- 
O 4- 




z 

o 

V) 2- 

T 


Po°° 0000 °7'' / 'x <, , / 

rV§o s y~r x \ J 








*1 + 2 + 3 + 4 + 5 + 6 + 7 
MEAN (0) 



Fig. 10. — Delineation of regions in the Malacca Strait based on textural properties as shown by the sand-silt- 
clay content and the relationship of sorting to mean grain size. 



114 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 



O o 96° 9 8 100 102 10 4 96 98 100 102 104 Q c 

o| 1 t-i «t n 1 r 1 | 1 n ^ r\ 1 1 1 o 




I \ 1 


\ 


\ COLOR 

CZH GRAYISH OLIVE 

V EEE3 OLIVE GRAY 
\ E3 LT OLIVE GRAY - 
.1 1113 DUSKY YELLOW 
M GREEN 

||\HI MEDIUM GRAY 


■ v \vz^r 


A 


C^^LyT 




"'*^N 






1 - 1 : 


^N. 1 





-6 



-4" 



-2 




100* 102° 

FlG. 11. — General description of total sediment, color, median diameter and sorting of surface sediments 
from the Malacca Strait and adjacent Andaman Sea. Median diameter and sorting are the descriptive measures 
of Inman (19521. 



made on the whole sample with the coarse and 
fine fractions separated by wet-sieving through a 
0.062 mm screen. The dried coarse fractions were 
further separated by sieving, and the fine frac- 
tions pipetted (Krumbein and Pettijohn, 1938, 
p. 165). The various measures used in this study 
to describe size distribution such as central 
tendency, dispersion and skewness follow the 
procedure recommended by Inman (1952). 
Median diameters and quartiles were picked 
from cumulative curves drawn on arithmetic 
probability paper. 

The effects of currents and debouching rivers 
on the depositional environment in the strait are 
clearly shown by the grain-size distribution 
pattern (fig. 11). Water depth appears to have 
little influence on the sediment distribution. Al- 
though the southern portion of the strait — 
Singapore to Port Swettenham — is a high- 
energy environment, it is nearly choked with 



fine material from the numerous rivers of Suma- 
tra that drain extensive low-lying areas of allu- 
vium. Clean coarse to very coarse sands are only 
found in the "Narrows," where a constriction 
occurs in the strait. In this region the currents 
often reach velocities of 140 cm/sec. which is 
sufficient for the removal of finer sediment. 

The large area of fine-grained sediment north- 
west of Penang Island, which extends westward 
beyond the axis of the strait, is a clear reflection 
of the general current pattern. The northwest 
current emerging from the narrow part of the 
strait tends to veer away from the Malayan 
Peninsula as it approaches the Andaman Sea. 
The southeast current from the Indian Ocean 
begins to enter the northern portion of the strait 
and then turns westward just north of Penang 
Island during the southwest monsoon. The re- 
sulting large eddy forms an area of lower current 
velocities and transport energy between the two 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



115 



westward moving currents (fig. 6). Clay-size 
sediments, with minor amounts of fine sand-size 
foraminiferal tests, predominate in the deep 
Andaman Basin. 

The percentages of sand-silt-clay clearly 
show the sediment variation in the major regions 
of the strait (fig. 10). In the Southern region, the 
finer size fraction is largely made up of lutite 
rather than silt-size material, indicating that the 
rivers in this section of the strait are carrying 
more clay- than silt-size particles. Silt, rather 
than clay-size material, comprises the bulk of the 
fine sediment in the Northern region. The South- 
ern region shows the effect of local drainage, 
while the Northern is more indicative of an 
environment farther from land in which the 
textural properties are related to the energy 
level rather than the sediment supply. The 
greater concentration of sand in the "Narrows," 
relative to all other regions, is indicative of the 
strong currents found there. The fine detrital 
sediment from local drainage into the "Narrows" 
apparently moves northward along the coast and 
does not reach the axial portion of the strait. 

Sorting. — Sorting is poor off the coast of Suma- 
tra particularly in the Southern region as a 
result of the sediment supply from rivers (fig. 
11) Low sorting values characterize the sedi- 
ments along the axis of the strait where the 
strong current and less fluvial material result in 
better sorting. Isolated patches of poorer or 
better sorted sediments can be related to topo- 
graphic depressions and elevations, respectively. 
Poor sorting in the vicinity of Penang Island is 
probably related to the current pattern dis- 
cussed above. 

Sorting related to mean grain-size shows the 
distinct characteristics of the four major en- 
vironments in the strait. Coarse sands are the 
best sorted whereas the fine silts are the poorest 
Sorting isopleths reveal a marked similarity to 
those of the median diameter, especially in the 
Southern region. 

Skewness. — A study of the areal distribution of 
skewness shows very little relationship to other 
measured parameters. Coarse and fine (negative 
and positive) skewness is found in both areas of 
sand- and clay-size material. The sands of the 
"Narrows" and the Central region of the strait 
are largely near-symmetrical to strongly coarse- 
skewed while in the Northern and Southern 
regions finely-skewed sediments predominate as 
the quantity of fine silt- and clay-size material 
increases. Sediments are fine-skewed, in the 
vicinity of some rivers although near others they 
are coarse-skewed even though the median di- 
ameters are similar. Skewness plotted against 



mean grain size indicates a general correlation 
between these two parameters and does suggest 
a sinusoidal relationship as has been reported by 
Folk and Ward (1957, p. 19) and Hubert (1964, 
p. 777). However, since this correlation is not 
more diagnostic than median diameter or sort- 
ing, it is neither illustrated nor further discussed. 

Organic Constituents 

Calcium Carbonate.— The fraction of the whole 
sample that is soluble in dilute hydrochloric 
acid is primarily organic material in the form of 
shell fragments and foraminiferal tests. Values 
are reported here as calcium carbonate, al- 
though minor amounts of magnesium carbonate 
may also be present. Acid-soluble fractions range 
from to 69 percent. Low concentrations (trace 
to 17 percent) occur throughout most of the 
strait. Two exceptions occur in the Central re- 
gion, where shells tend to concentrate on banks 
and to the north, where there are more shell 
fragments and foraminiferal tests (fig. 12). 

Areal distribution of calcium carbonate bears 
little or no relationship to any of the textural 
parameters because of its biogenic origin. The 
lowest percentages are found in the narrow por- 
tion of the strait where calcium carbonate may 
be completely absent, possibly because of strong 
currents that break-up and winnow-out shell 
fragments. Low calcium carbonate percentages 
in the vicinity of large rivers results from the 
high sedimentation rate of fine material that is 
detrimental to the living habits of shell-con- 
tributing organisms. The carbonate concentra- 
tion increases both to the south of the strait and 
to the north into the Andaman Basin where the 
calcium carbonate fraction consists mainly of 
foraminiferal tests. 

Although shells and foraminiferal tests are 
present in most samples, they constitute only a 
small percent of the entire sample and are often 
masked by large quantities of fine detrital mate- 
rial. 

Shells. — The areal distribution of both shell 
fragments and foraminiferal tests (fig. 12) re- 
sembles that of total calcium carbonate: each is 
absent in the "Narrows," most abundant in the 
Northern and Southern regions, and of inter- 
mediate abundance in the Central portion except 
for two isolated areas with relatively high con- 
centrations. Mollusks contribute the major por- 
tion of the shell material; pelecypods are the 
predominant forms in shallow water and gastro- 
pods are more commonly found in deeper water. 

Foraminifera. — Foraminiferal tests are particu- 
larly abundant in the Andaman Sea and in the 
Northern region; their numbers decrease to the 



116 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 




96 98 100 102 104 



96 98 100 102 104 



Fig. 12. — Surface distribution of calcium carbonate, shell, foraminifera, and organic 
carbon, Malacca Strait and adjacent Andaman Sea. 



southeast. The shelf break is a distinct divide 
between the high-test concentrations in the 
Andaman Sea and the relatively low abundance 
in the strait. The tongue-like area of forami- 
niferal tests projecting into the strait from 
the Andaman Sea is attributed to the environ- 
ment caused by the wedge of cool, high salinity 
bottom water that also extends from the Anda- 
man Sea into this region (fig. 8). 

Organic Matter. — Duplicate organic carbon de- 
terminations were made using the potassium 
dichromate-ferrous ammonium sulfate titration 
method of Allison (1935). The values obtained 
are only approximate because this method is 
based on the assumption that all organic matter 
in sediments is at the same state of oxidation. 
Percentages of organic carbon range from 0.01 to 
2.71. The lowest concentrations are found in the 
area of maximum current velocity between Port 
Swettenham and Malacca (fig. 12). A fair cor- 



relation exists between the areal distribution of 
grain size and organic carbon; low organic car- 
bon normally is associated with the coarser 
sediments. High organic carbon content along 
portions of the coastal margin reflects the in- 
fluence of river discharge. This is particularly 
evident in the Southern region and north of 
Penang Island. Isolated areas of relatively high 
organic carbon also occur where organic matter 
has collected in topographic depressions. A pro- 
nounced deficiency of organic carbon occurs 
along the shelf break where the currents tend to 
winnow away the finer material. Organic carbon 
percentage increases beyond the continental 
shelf towards the Andaman Basin. 

Nitrogen content was determined for 77 sur- 
face samples using a modified micro-Kjeldahl 
method (Henwood and Garey, 1955). Values 
ranging from a trace to 0.235 percent, all of 
which is considered to be organic nitrogen. Areal 
distribution of nitrogen content throughout 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



117 



8 









100 



102 



Fig. 13. — Surface distribution of nitrogen and carbon to nitrogen ratio, 
Malacca Strait and adjacent Andaman Sea. 



104 



o u 



most of the strait is usually less than 0.050 per- 
cent (fig. 13). Lowest values occur in the coarse 
to medium sands in the "Narrows" and in the 
sands along the shelf break. A noticeable in- 
crease in nitrogen is observed in the Southern 
region along the Sumatra coast where organic- 
rich sediments are deposited from nearby rivers. 
Values to the north increase in areas of finer 
sediment with the highest percentages occurring 
in the Andaman Basin. 

In the Malacca Strait, C/N ratios vary be- 
tween 0.4 and 36.9; smaller values occur in the 
"Narrows" (fig. 13). High ratios are found along 
the Sumatra coast and in the vicinity of Penang 
Island indicating abundant drainage from 
nearby streams of terrestrial humus, such as 
peat, which is often found disseminated through- 
out the finer sediments. Carbon-nitrogen ratios 
of 56 samples give a mean of 15.4, which is 
slightly higher than the mean of 13 found for the 
Gulf of Thailand sediments (Emery and Niino, 
1963, p. 548) and considerably higher than the 
8.4 reported by Trask (1932, p. 21) for all Re- 
cent marine sediments. The large mean found in 
the Malacca Strait is attributed to the high in- 
flux of high-carbon organic matter from rivers 
draining areas of heavy vegetation. 

Although organic carbon and nitrogen content 
is indicative of the amount of total organic 
matter present in the sediment, there is no con- 
sensus as to the proportion of these constituents 
in organic matter (Bader, 1954; Kaplan and 
Rittenberg, 1963, p. 593). For this reason, no 
attempt is made here to determine the total 
organic content, but only to show its relative 
concentration by means of the organic carbon 
and nitrogen content. 



Sponge spicules are the dominant siliceous 
organic remains in these samples. They are most 
abundant in the Central and Northern regions 
where, however, they constitute only a very 
small percentage of the whole sample. Minor 
amounts of radiolaria are found in most samples; 
larger numbers occur in samples from the Anda- 
man Sea and the Northern region. 

Vertical variation of organic constituents is 
only significant in core samples that penetrate 
the stiff, silty clay underlying the coarser Recent 
sediments. A noticeably lower calcium carbonate 
content is almost always found in the underlying 
clay. Organic carbon and nitrogen content is 
generally higher in the clay than in the overlying 
sediment in most areas, except in the Southern 
region where the reverse is true. Variation of the 
C/N ratio between the sediment above the clay 
and in the clay may amount to a factor of four. 

Variation of the sedimentary parameters with 
depth is often masked or completely altered by 
burrowing organisms. Burrow holes or passages 
are readily apparent in many cores owing to the 
sharp contacts between the coarse material fill- 
ing the passages and the finer surrounding sedi- 
ment. Organisms appear to have dragged the 
coarser surface sediment downward in some 
areas. In others, they have apparently con- 
centrated the quartz and volcanic glass shards 
from the finer sediment through which they are 
burrowed. Mottling, which is commonly an indi- 
cation of organism activity is quite noticeable in 
the finer sediments of the Andaman Basin, but is 
not observed in cores taken from the strait. The 
presence or absence of mottling is attributed to 
the different forms of burrowing organisms and 
the types of sediment found in the two areas. 



118 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 







Table 1 


. — Mineralogy 


of the 


coarse 


frac 


ion from various 


regions 


9/ </*e Malaccc 


-SI 


raj7 




















a 


nd the 


southern part of the Andaman B 


isin 
























Percent Light Mineral Fraction 








Percent Heavy 


Mineral Fraction 










rt 












e 
'3 

E 




c 































< 

c 


c 




u 


rt 




(5 




°| 


a 


.- CD 


a; 


c 

*rt 






CD 




g 


V 


<D 


<u 


* 


t,' *~" 


o 

rt 


o 
c/5 


rt 

a 


o 

6 


o 
rt 


o 


S 

rt 

CO 

O 


6 


a Jj 

J to 

£8 


o 


c e 

CD CO 

E « 


2 
a 
E 

< 


E 
o 


c 
o 

N 


c 
rt 

o 


O 

s 




'2 

rt 


(/} 


15 

CD 
O 
O 


O 


£8 


c 


1 


44 




tr 


4 


38 


14 


99.6 


60 


17 


7 


3 


2 






1 


3 






5 


2 


0.4 


<u c: 


3 


tr 




tr 


2 


98 




99.7 


74 


19 


4 


1 


2 


















0.3 


J3 O 


6 


28 


tr 


tr 


18 


36 


18 


98.2 




1 


















98 






1.8 


i'8 


9 


64 


tr 




17 


17 


2 


97.9 
























100 




2.1 


°£ 


179 


93 


6 


1 


tr 






99.8 


35 


37 




4 




6 




18 




tr 








0.2 


6 


11 


100 


tr 










97.8 


3 


9 




1 










1 






86 




2.2 


5 


47 


98 








tr 


2 


98.8 


5 


10 




2 










tr 






83 




1.2 


12 


88 


2 




1 


8 


1 


99.6 


32 


31 


3 


7 


6 








19 








2 


0.4 




16 


47 


2 


tr 


7 


16 


28 


96.0 














100 














4.0 




18 


1 


tr 


tr 


20 


36 


43 


99.7 


17 


4 


39 


7 


6 




2 


1 


16 


5 






5 


0.3 


ri ^ 


20 




3 


tr 


1 


93 


2 


99.7 


20 


12 


22 


3 


7 




15 




12 


5 






4 


0.3 


Sh o 


184 


86 


8 


2 


2 


2 


tr 


98.9 


44 


33 


4 


6 


3 




7 




1 








2 


1 .1 


c'wi 


188 


73 


5 


13 


7 


tr 


2 


99.0 


19 


42 


5 


4 


2 




20 




7 








1 


1 .0 


ua 


196 


43 


1 


1 


IS 


32 


7 


99.7 


tr 




tr 




tr 




99 












tr 


0.3 


c 


23 


77 


3 


tr 




20 




99.7 


30 


11 


3 


11 










39 








6 


0.3 


5.2 


24 


66 


3 


tr 


tr 


21 




99.4 


31 


2 


24 


9 






6 




24 








4 


0.6 


25 


92 


S 


tr 


tr 


3 




99.4 


26 


16 


24 


6 






6 




18 








4 


0.6 


1 •» 


214 


94 


3 




tr 




3 


99.7 


32 


19 


6 


6 


4 






1 


27 








5 


0.3 


Is 


211 


5 






S 


90 




99.7 


31 


15 


23 


4 


2 








23 








2 


0.3 


26 


5 






2 


93 




98.9 


7 


24 


25 


8 








1 


30 








5 


1.1 


•O c/i 


208 


31 


3 


tr 


1 


65 




97.6 


5 


8 


50 


22 






9 


2 


1 








4 


2.4 


<m 


209 


5 








95 




96.6 


4 


89 


3 




1 








3 










3.4 



* Glauconite, volcanic glass 

** Allanite, Andalusite, Cassiterite, Corundum, Epidote. Monazite, Muscovite, Pyrite. Sillimanite, Titanite, Topaz 



Disturbances due to organisms are observed to a 
depth of 84 cm in cores from the strait, while in 
the soft sediments of the Andaman Basin, mottl- 
ing attributed to organisms is found as deep as 2 
m below the sea floor. 

Detrital Constituents 

Separation of the sand-size particles into light 
and heavy mineral fractions was made by a 
heavy liquid technique using tetrabromoethane 
(specific gravity 2.96). The light minerals were 
identified by the staining technique described by 
Laniz, Stevens, and Norman (1964), and ex- 
amination under a binocular microscope. Heavy 
mineral fractions were weighed and their weight 
percent in the total sand sample determined. 
Identification of the mineral constituents was 
made using a petrographic microscope. The re- 
sults of this examination are given in table 1. 

Light Minerals. — Light minerals dominate the 
coarse sediment fraction (75 to 100 percent by 
weight) and are generally concentrated in the 
sands along the axis of the strait. Quartz com- 
prises over 50 percent of the light fraction in all 
but a few samples and makes up the entire 
sample in the high energy zone between Port 



Swettenham and Malacca. An area of low quartz 
content (1 to 35 percent) and high glauconite, 
volcanic glass and shell fragments extends across 
the strait from Belawan to Penang Island. 
Isolated areas of low quartz content sediments 
are observed in the Northern region in topo- 
graphic depressions where shell material pre- 
dominates. Quartz content is also low in the 
southern entrance to the strait (trace to 44 per- 
cent). 

Orthoclase is generally more abundant than 
plagioclase; concentrations of a trace to 9 per- 
cent are found in the Central and Northern re- 
gions, and a trace in the Southern region. Trace- 
able amounts of plagioclase occur throughout 
the strait with a few samples along the Malay- 
sian coast, north of Port Swettenham, containing 
as much as 5 to 13 percent. The other few sam- 
ples in which plagioclase dominates over ortho- 
clase occur in low energy environments either 
close to shore or in topographic depressions. No 
distinct distribution pattern can be detected for 
either of the feldspars as a result of the numerous 
rivers and the different areas drained by these 
rivers. 

Heavy Minerals. — With a few exceptions, the 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



119 



heavy mineral assemblages present are composed 
of stable to moderately stable minerals derived 
from intermediate to silicic igneous rocks and 
from associated crystalline metamorphic rocks. 
These rocks are abundant in both the bordering 
land provinces and the islands at the southern 
entrance to the strait. However, in view of the 
lack of information concerning coastal detritals, 
only generalizations can be made about prove- 
nance. 

A few minerals dominate the assemblages in 
most instances. Opaques consisting of leucoxene, 
ilmenite and magnetite constitute large percent- 
ages of the majority of the samples. It is be- 
lieved that most of the black opaques are ilmen- 
ite rather than magnetite because of the ob- 
served partial alteration to leucoxene of many 
grains of similar appearance. The percent of 
leucoxene compared to ilmenite is high in two 
areas: the extreme southern end of the strait and 
a large area occupying the north-central axial 
portion of the strait and extending beyond the 
shelf into the Andaman Sea. This relationship is 
reversed towards the coastal margins and south- 
ward from the Northern region of the strait. 

Biotite is concentrated in an elongate area 
paralleling the northern Sumatra coast and in 
another area beyond the shelf in the Andaman 
Sea. Large hexagonal books of biotite are found 
to make up an entire heavy fraction of a surface 
sample collected in this area off the Sumatra 
coast. These concentrations indicate an adjacent 
source, possibly entering from the nearby Asa- 
han River of Sumatra. The northwesterly cur- 
rent in the strait may account for the northward 
distribution of the biotite along the coast and 
into the Andaman Basin. 

Amphiboles and staurolite occur in high per- 
centages in most samples from the northern and 
central portions of the strait. The largest quan- 
tity of staurolite is found in the north while 
amphiboles are concentrated in the west-central 
strait area; a source for both minerals in the 
crystalline schists of Sumatra is suggested. 
Tourmaline is usually found in relatively high 
concentrations (3 to 13 percent) in association 
with staurolite. Both minerals are also abundant 
in the vicinity of the Rokan River, indicating a 
possible source in the metamorphics of the 
Barisan Range of Sumatra. 

Heavy fractions from the "Narrows" are 
composed almost entirely of siderite or goethite. 
A few of these grains contain an olive-brown 
rounded aggregate of minute crystals, while 
others have a similar oval shape with colors 
varying from yellow-brown and brownish-red to 
brick-red, and display an earthy surface appear- 
ance. Chemical tests on selected grains of the 
olive-brown material show it to be siderite. X- 



ray analysis of these various grains indicate 
siderite in some cases and goethite in others al- 
though the outward appearance of the grains is 
similar. Alteration of the siderite appears to be 
the answer, with oxidation of the ferrous iron 
and leaching of carbonate. Partial alteration has 
masked the surface of some grains and gone to 
completion in the crystallization of goethite in 
the other samples. 

Heavy-mineral weight percentages of the total 
sand-size fraction are low, generally less than 
one percent, and correlate with the relative 
abundance of medium to fine sand. Heavy min- 
eral concentrations greater than 1 percent are 
confined, with few exceptions, to those samples 
in which a single mineral comprises all or nearly 
all of the heavy-mineral fraction. 

Van Baren and Kiel (1950) divided the sedi- 
ments of the Malacca Strait into three distinct 
groups based on the mineral suites from 18 
samples. Their results are not corroborated by 
the present study (table 1). 

In an environment like the Malacca Strait, 
with its large number of debouching rivers and 
varied sediment source areas, it is not believed 
that distinct mineral suites can be delineated for 
the major portion of the area. Some distinction is 
possible, however, in the Northern region where 
the effect of reduced local drainage is shown by 
the distribution of the amphibole-staurolite- 
tourmaline suite that does appear to have a def- 
inite distribution. 

Clay Minerals. — The clay minerals were identi- 
fied in 54 surface samples as well as in selected 
intervals from four cores by means of X-ray 
diffraction. 

The less-than-two micron fraction was taken 
from samples which had been treated with 
sodium hexametaphosphate and used for the 
grain-size analyses. Two glass slides of oriented 
aggregate were prepared from each sample. Each 
set of slides was X-rayed (Cu Ka radiation) after 
drying at room temperature and again after 
solvation in ethylene glycol. Additional X-ray 
analyses were obtained from selected samples 
treated in warm 8 N HC1. 

The clay minerals observed in this study — 
montmorillonite, kaolinite, undifferentiated 
mixed-layer minerals, illite and chlorite — were 
identified by their characteristic X-ray diffrac- 
tion peaks. 

Clay minerals of the montmorillonite group 
were identified by a (001) peak reflection which 
shifts to 17A after ethylene glycol treatment. 
However, this could be a true montmorillonite or 
an illite and/or chlorite which has been stripped 
of its inter-layer cations and now absorbs two 
layers of ethylene glycol (Griffin and Goldberg, 



120 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 






UNTREATED 

3.6 5 7 A 



CENTRAL 




ETHYLENE GLYCOL 

3.6 5 7 A 



Sta 195 
(0-5 cm) 



Sta 204 
(40-43c 



Sta 209 
(1-3cm 



Sta 179 
(0-13 cm) 



Sta 184 
(0-6 cm) 




Fig. 14. — Typical X-ray diffraction patterns of clays from various parts of the Malacca Strait 

and adjacent Andaman Sea. 



1963). Diffraction peaks at 7 and 3.5k are 
attributed to kaolinite. Using a modification of 
the procedure described by Brindley (1961, p. 
264), a representative number of the samples 
were placed in warm 8 N HC1 for two hours and 
then X-rayed to distinguish between kaolinite 
and chlorite. Broad, asymmetrical diffraction 
peaks varying between 15.5 and 16. 8A after 
ethylene glycol solvation characterized the un- 
differentiated mixed-layer minerals. These con- 
sist of a complex grouping of three-layered min- 
erals interlayered with montmorillonite. It ap- 
pears that illite may be the significant mineral 



mixing with montmorillonite, although chlorite 
is undoubtedly also present. Diffraction peaks at 
10, 5 and 3.3A which are not affected by ethyl- 
ene glycol treatment are defined here as belong- 
ing to minerals of the illite group. A diffraction 
peak at 4.7A as well as a slight reduction of the 
3.5A peak after acid treatment is used as evi- 
dence of chlorite. Typical X-ray patterns for 
samples from different regions of the Malacca 
Strait and Andaman Sea are shown in figure 14. 
A semi-quantitative determination was made 
utilizing the intensities of the X-ray peaks to 
study the clay-mineral distribution. The pro- 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



121 



cedure used is similar to that described by 
Johns, Grim, and Bradley (1954), with the ex- 
ception that the area of the 1 7 A peak was di- 
vided by three rather than four. This procedure 
was used by Ferrell (1965, p. 21-22) and found 
to be satisfactory. Values are reported in percent 
rather than in parts in 10 as a matter of con- 
venience. This method, although not truly 
quantitative, is suitable for comparison of rela- 
tive abundance. 

Kaolinite, mixed-layer minerals, illite, mont- 
morillonite and chlorite comprise the clay- 
mineral assemblage found in the Malacca Strait 
in order of decreasing abundance. Kaolinite and 
mixed-layer minerals constitute from 60 to 85 
percent of the clay minerals present in most 
samples. Illite is present in all samples, but is 
never found to be the dominant clay mineral. 
Montmorillonite is the predominant clay min- 
eral at only a few locations and combines with 
other minerals to form the mixed-layer minerals 



in all other samples. Chlorite was only observed 
in trace amounts although it is present in many 
samples. 

The highest concentrations of kaolinite are 
observed in the shallow areas along the Sumatra 
coast and in the southern portion of the strait 
(fig. 15). Kaolinite is common in all samples as 
might be expected of sediments collected rela- 
tively close to land in a tropical climate. The 
kaolinite content bears a close relationship to 
the isobaths; a decrease in kaolinite occurs with 
increasing water depth. Minor concentrations 
are found in the Andaman Basin. Undifferenti- 
ated mixed-layer minerals constitute the domi- 
nant clay minerals in the Northern and deeper 
portions of the strait as well as in the southern 
part of the Andaman Basin (fig. 15). However, 
mixed-layer minerals comprise a large portion of 
the clay minerals in most of the samples ana- 
lyzed. Montmorillonite is the predominant clay 
mineral at only six stations, all of which are 



96° 98° 100° 102° 104° 9 6° 98° 100° 102° 104° 



\ PREDOMINANT 
CLAY MINERALS 

i*\ WW KAOLINITE 

I | MIXED-LAYER 
MONT 




\ MIXED -LAYER 

i: C/o CLAY FRACTION) 




96° 98° 100° 102 



104 C 




100° 102 C 



Fig. 15. — Surface distribution of the predominant clay minerals, kaolinite, mixed-layer minerals 
and illite in the Malacca Strait and adjacent Andaman Sea. 



122 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 



close to shore and generally in the vicinity of 
river mouths. The concentration of montmoril- 
lonite (46 to 53 percent of the clay minerals) in 
the southern portion of the strait decreases 
away from the rivers. Drainage through the 
Tertiary tuffs on Sumatra provides the probable 
source material for these clays. Streams drain- 
ing Permian shales on the Malay Peninsula in 
the vicinity of Penang and Langkawi Islands may 
be responsible for the montmorillonite in this 
area. Although illite is present in all the samples 
it seldom makes up more than 25 percent of the 
clay minerals and usually is much less. The 
largest concentrations of illite are found east of 
northern Sumatra in an area where sediments 
also contain large amounts of biotite. This as- 
sociation plus the presence of glauconite, which 
is mentioned later, may indicate a diagenic 
relationship between these minerals (Burst, 
1958, p. 493). The illite and biotite could also 
have been transported to the strait from a source 
area in Sumatra. 

The montmorillonite peak in samples col- 
lected progressively farther from land in the 
Southern region is observed to lose its character 
and assume that of a mixed-layer peak. This 
change may be caused by the occurrence of de- 
graded illite with the montmorillonite. The pres- 
ence of degraded illite can be explained by the 
loss of potassium ions during transport in 
slightly acid river waters. As the rivers empty 
into the strait these ions are normally regained 
(Bradley, 1953). Although degraded illite may 
fix potassium from the sea water in a matter of 
days as suggested by Weaver (1958), it might be 
a long time before the illite has completely 
achieved its characteristic 10A peak. In such a 
situation, the presence of a certain amount of 
degraded and crystalline illite would cause the 
montmorillonite peak to broaden and assume 
the characteristics of a mixed-layer mineral. 
The amount of magnesium ion fixation by 
chlorite could have a similar effect on the mont- 
morillonite peak (Grim and Johns, 1954, p. 100). 

Four cores ranging in length from 0.8 to 3.5 m 
were examined for their clay mineral content, 
and, of these, only three showed any discernible 
variation with depth. The predominant minerals 
are the same as those found in the surface sedi- 
ments. 

The percentage of mixed-layer minerals in- 
creases slightly and illite decreases with depth in 
the three cores. It is generally reported in the 
literature that there is little or no variation in 
clay mineral composition with depth for cores in 
Recent marine sediments (Emery, 1960, p. 231; 
Griffin and Goldberg, 1963, p. 739; Heezen, and 
others, 1965, p. 5821). This unusual occurrence 
found in the Malacca Strait may possibly be ex- 



plained by an upward migration of slightly acidic 
water that strips potassium ions from the illite. 
This would result in a decrease in 10A illite and 
an increase in the mixed-layer minerals. Each of 
the cores displaying this change with depth con- 
tains some finely disseminated peat which would 
reduce the pH of the interstitial water. 

Volcanic Fraction. — Volcanic material found in 
the sand-size fraction consists mainly of shards of 
volcanic glass and pieces of pumice. Shards are 
colorless and triangular, plate-like or irregular in 
shape and often have inclusions of oval-shaped 
bubbles. The refractive index is 1.512 + 0.002. 
Glass of the same refractive index consists ap- 
proximately of 67 percent silica and is derived 
from an andesitic magma according to George 
(1924). 

Glass shards occur in almost all the samples in 
amounts varying from a trace to 25 percent of 
the light fraction. The highest concentration is 
found along the Sumatra margin of the strait 
between the Asahan River and Belawan, where 
percentages range from 10 to 25. 

Volcanic glass is also quite common in many 
cores where its presence is clearly noted by the 
numerous layers of glass shards. These layers are 
very distinct owing to their light gray color in 
contrast to the darker surrounding material. Ash 
layers vary in thickness from 0.1 to 4 cm, but are 
usually less than 0.25 cm thick (fig. 16). 

There appears to be a correlation of an ash 
layer, occurring at a depth of 30 cm below the 
sea floor, among three adjacent cores from the 
Central region of the strait. This may be a coin- 
cidence because it is not seen in nearby cores, 
and other ash layers cannot be traced from one 
core to another. A 4 cm-thick ash layer found in 
the bottom of core 103 probably represents a 
local deposit in a former topographic depression 
because it is not observed in adjacent cores less 
than 3.2 km away. Shards are also concentrated 
in irregular bands or pockets that are probably 
the result of burrowing organisms. 

Light gray layers similar in appearance to the 
ash are observed in certain parts of the strait. 
These layers, however, are largely composed of 
clean quartz and glass shards of a single grain 
size (4 phi). Such is the case west of Singapore 
where, upon initial examination, the cores look 
much the same as those containing layers of 
shards, but on closer scrutiny clean quartz 
rather than volcanic glass is found to be the 
dominant constituent. Similar occurrences of 
such layers are found in a few cores from the 
Central region of the strait. 

It is believed that the ash layers do not rep- 
resent wind-borne tephra erupted from nearby 
volcanoes, but rather detrital deposits of ash 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



123 



eroded from the neighboring land areas. Large 
ash concentrations off the Sumatra coast in the 
vicinity of rivers draining tuff deposits on 
Sumatra lends support to this conclusion. The 
numerous ash layers in relatively short intervals 
of the core section, 25 laminae in a 10 cm in- 
terval, may be more indicative of heavy runoff 
during the monsoons than volcanic eruptions. 
Reworking by currents may also account for the 
ash distribution. 

Authigenic Constituents 

Glauconite is found extensively throughout 
the strait occurring mainly as pellets of dark- 
green grains and to a lesser extent occupying 
the cavities of foraminiferal tests. Percentages of 
glauconite range from a trace to 80 percent of 
the light fraction with a mean of about 6 percent. 
The highest concentrations occur in the Central 
region along the Sumatra margin. Only traceable 
amounts are found in the coarser sediments be- 
tween Malacca and Port Swettenham. No ap- 
parent correlation is observed between the occur- 
rence of glauconite and grain size because of the 
way in which the pellets are deposited. Glau- 
conite pellets become part of the sediment as the 
foraminiferal tests surrounding the pellets are 
broken. Most of the broken tests are winnowed 
away leaving the pellets behind. Excluding the 
narrow portion of the strait in the vicinity of 
Port Swettenham, there appears to be a general 
inverse relationship between the presence of 
foraminifera and glauconite as a result of the 
removal of the broken tests. 



Pyrite occurs in the form of internal molds of 
foraminifera and radiolaria and is frequently 
found in the surface sediments. The possibility 
that reducing conditions may exist in the micro- 
environment within cavities of various tests and 
shells may be significant in explaining the origin 
of such authigenic minerals as pyrite and glauco- 
nite in an environment often oversaturated with 
oxygen. Emery (1960, p. 267) reported similar 
occurrences of pyrite off the coast of southern 
California. No indication of phosphorite or 
manganese oxide coating of gravel was observed 
in any of the samples. 

PLEISTOCENE-RECENT HISTORY 

The Malacca Strait is a part of the Sunda 
Shelf, which is one of the major continental 
shelf areas of the world. This shelf, unlike most 
others, is believed to have been a peneplain 
formed in the Late Tertiary or Early Pleistocene. 
The peneplain was further denuded during the 
Pleistocene, when sea level was lowered between 
73 and 91 m (Dickerson, 1941, p. 30). The 
present Sunda Shelf was drowned and the 
Malacca Strait, as it is essentially found today, 
came into existence as a result of the postglacial 
eustatic rise of sea level. Molengraaff (1921, p. 
100) suggests that no crustal movement was in- 
volved in the submergence. The rather uniform 
depth of the shelf, between 55 and 64 m, and the 
numerous drowned river valleys tend to support 
this hypothesis. Additional evidence from a 
study of Pleistocene geology on Sumatra and 
Java by Smit Sibinga (1952) lends further cre- 




FiG. 16. — Volcanic ash layers in the cores from the Central region of the Malacca Strait. 



124 



GEORGE H. KELLER AND ADRIAN F. RICHARDS 



CaCO- 
1?3P.qp 




Organic Carbon 
4 . .8 . 12. 1.6,2,0. 



Nitrogen 

(%) 

.03 ,.0,5, 



RECENT i 



PLEISTOCENE 



STATION 112 

Md 

(0) 
34.5 6 78 910 



Sand 




Silt 
Clay 


Sorting 


(%) 


(0) 





10 

_20 

40- 
50- 
60- 

STATION 130 



CaC0 3 

100 2 3 4 20 

i i ,i 



Organic 
Carbon 

1.2 16 2.0 



"i 



tffiijjj 

FfHIJIJ 
tipJJJJl 
fc=iJH/J 



/ 

T 

i 



~T 



RECENT 

T ■ T 

l\PLEISTOCENEi 

\ \ 



( 1 SUBSAMPLE INTERVAL) 



Nitrogen 

(%) 
05 07 

i i I 



Fig. 17.- — Vertical variation of textural and chemical properties in cores penetrating the Pleistocene sediments. 



dence to the hypothesis. A carbon-14 date for 
peat found in a core approximately 24 km north 
of Port Swettenham at a depth of 26.5 m below 
sea level gave an age of 10,000 + 200 years B. P. 
(U. S. Geological Survey No. VV-1675). This date 
is on the curve established by Curray (1960) and 
Shepard (1960) for the rise of sea level since the 
Late Quaternary. It is evident that the Malacca 
Strait has remained stable during the last 10,000 
years. 

Evidence of the Pleistocene-Recent history is 
seen in many core samples as well as in the 
bathymetry of the strait. Numerous cores ex- 
hibit two distinct sediment layers: an upper layer 
of sand with shell debris and an underlying stra- 
tum of stiff, silty clay. The sand is characteristi- 
cally dirty and composed of medium to fine sand- 
size particles of quartz, shell debris, glauconite 
and rock fragments. The underlying gray silty 
clay is relatively clean and contains only minor 
or traceable amounts of shell fragments, glau- 
conite and rock fragments. Peat is usually dis- 
seminated throughout the silty clay both as fine 
particles and as large fragments of wood or plant 
roots. The lower 15 cm of core 185, from just 



north of Port Swettenham, was entirely com- 
posed of peat. In many cores the silty clay sec- 
tion is relatively stiff and appears to have be- 
come indurated before the overlying sand was 
deposited. The pronounced change in sedimen- 
tary characteristics across this contact is quite 
evident from figure 17. 

These two types of sediment are indicative of 
two distinctly different environments of deposi- 
tion. The silty clay with its abundant peat and 
few shell fragments is similar to that found in 
some tidal flat or estuarine areas today (Hantz 
schel, 1939, p. 197; Guilcher, 1963, p. 624; Van 
Straaten, 1963, p. 164). The overlying coarse 
sediments represent the present high energy 
environment of the strait. We believe that the 
stiff clay represents a Late Pleistocene tidal flat 
or estuarine deposit, which is in agreement with 
the Pleistocene paleogeography proposed by 
Molengraaff (1921) for this area. The stiffness of 
the clay indicates that it may have been partially 
indurated as a result of being subaerially exposed 
for some period prior to its submergence. This 
material was probably eroded during the period 
of exposure and the drainage pattern now ob- 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 



125 



served in the present bottom topography is a re- 
sult of that erosion. As a result of the radiocar- 
bon date mentioned earlier, from a peat sample 
taken 23.5 cm below the sand-clay contact, it 
seems feasible that the stiff, silty clay is of Late 
Pleistocene age. 

The depth at which this Pleistocene surface oc- 
curs below the present strait floor differs con- 
siderably depending on the local rates of de- 
position in the strait. The surface is often found 
at depths of less than 20 cm in the axial portion 
of the strait, while between Langkawi and 
Penang Islands it occurs at a depth of 41 cm. 
Cores that do not display any indication of this 
surface may not have penetrated deep enough, 
or the surface may have been obliterated by 
burrowing organisms. 

CONCLUSIONS 

The sediments in the Malacca Strait are 
largely derived from the adjacent land provinces 
of Sumatra and the Malay Peninsula where the 
geologic condition varies considerably. Minor 
amounts of sediment are also transported into 
the strait from the islands south of Singapore. 

Although the Malacca Strait is in a part of the 
world where monsoons strongly influence clima- 
tological and oceanographic conditions, little 
direct effect is observed because of the protection 
provided by the bordering land masses. The cur- 
rent circulation is mainly caused by the move- 
ment of water into the strait from the South 
China and Java Seas and to a lesser extent from 
the Andaman Sea. The depositional environment 
is primarily influenced by the currents and the 
numerous streams draining into the strait. Al- 
though rivers account for the movement of most 
sediment into the strait, as well as along its 
coastal margins in some sections, a northwest 
current provides the mode of transport for the 
sediments within the strait. Deposition of bio- 
genic constituents, however, shows a greater 
dependence on the physical and chemical char- 
acteristics of the overlying water mass. This is 
evident from the similarity of the foraminifera 
distribution with that of a pronounced wedge of 
cool-temperature, high-salinity water extending 
into the strait from the Andaman Sea. 

The depositional environment of the Malacca 
Strait can be divided into four regions based on 
the textural parameters of the surface sediments: 
Northern, Central, "Narrows" and Southern. 
Each region also shows a difference in oceano- 
graphic conditions as well as in the influence of 
streams on the environment. Sediment distribu- 
tion in the Northern region is almost entirely 
controlled by currents; in the Southern region 
both currents and local streams are the con- 
trolling factors. 



The significance of sediment color in the 
Malacca Strait is not as an indication of the con- 
ditions in the depositional environment, as is 
often reported in the literature (Emery, 1960, 
p. 234; Niino and Emery, 1961, p. 749), but 
rather as a property of the sediments entering 
the strait. Various streams are depositing sedi- 
ments of different colors, which is clearly shown 
by the sediment color distribution in the strait. 

Organic matter is generally concentrated in 
the vicinity of river mouths or in the deep 
Andaman Sea. High carbon to nitrogen ratios 
near debouching rivers are an indication of the 
greater abundance of high-carbon, terrestrial 
organic matter being deposited in these areas. 
Peat is believed to be the source of the organics. 
The lower ratios in the Andaman Sea sediments 
are attributed to the partly decomposed remains 
of marine plankton and benthos. 

The mineralogy of sediments in the strait is 
complex because of the numerous streams drain- 
ing the varied geology on the Malay Peninsula 
and Sumatra. Delineation of mineral suites is 
particularly difficult because of the interfinger- 
ing of the sediments from these streams. Only 
along the western margin of the Northern and 
Central regions of the strait can any inference be 
made as to sediment provenance based on the 
mineral suites. The concentration of amphiboles, 
staurolite, tourmaline and biotite in these re- 
gions suggests a possible source in the metamor- 
phics of the Barisan Range of Sumatra. Sumatra 
rather than the Malay Peninsula appears to be 
the predominant source area for the detrital 
sediments in the strait. 

Kaolinite is the predominant clay mineral 
found in the strait, as would be expected in 
marine sediments derived from land masses in a 
tropical climate. Undifferentiated mixed-layer 
clay minerals are abundant in the deeper areas 
as the result of what appears to be the combin- 
ing of montmorillonite with degraded illite and 
possibly chlorite. Most of the clay minerals are 
detrital although some of the illite may be a 
diagenic product of glauconite. 

Slight increases in the percent of mixed-layer 
minerals and decreases in the illite content with 
depth are believed to be due to leaching of 
potassium ions from the illite in an inferred acid- 
ic environment. The degraded illite then com- 
bines with the montmorillonite to form the 
mixed-layer minerals. 

Although volcanic glass is found throughout 
most of the strait no ash layers can be traced 
over any great distance. The layers are normally 
very thin (0.25 cm) and are repeated frequently 
in a cored interval. This evidence, together with 
an increase in ash concentration off some of the 
rivers, indicates that most of these sediments are 



126 GEORGE H. KELLER AND ADRIAN F. RICHARDS 

carried into the strait by streams draining tuff acknowledgements 
deposits rather than being wind-borne material 

from nearby volcanoes. The numerous layers in We gratefully acknowledge the assistance of 

a short core interval may possibly reflect sea- Mr. Richard Stewart and others of the Oceano- 

sonal changes in runoff. The lack of eolian ash graphic Division of the U. S. Naval Oceano- 

deposits is attributed to the strong water cur- graphic Office who collected much of the field data 

rents that do not allow the ash to settle into dis- and performed many of the textural and chemi- 

tinct layers as is found in some deep-sea sedi- cal analyses. Thanks are also extended to Dr. 

ments. Kelvin Rodolfo for carrying out the nitrogen 

Authigenic minerals such as glauconite and analyses and to Dr. Meyer Rubin for the car- 

pyrite are common constituents of the sediments bon-14 determination. Discussions with Dr. J. B. 

in the strait. These minerals are all believed to Alexander of the Malaysian Geological Survey 

have formed within the tests of foraminifera and proved most helpful during this investigation, 

radiolaria and do not, by their presence, suggest We acknowledge with appreciation the assis- 

a reducing environment. tance of Professors A. V. Carozzi, R. E. Olson, 

The Sunda Shelf, of which the Malacca M. F. Wahl and H. R. Wanless of the University 

Strait is a part, is, believed by many investiga- of Illinois who critically read and made helpful 

tors to represent a Tertiary-Quaternary pene- suggestions to this manuscript 

plain drowned as a result of an eustatic rise of sea The U. S. Naval Oceanographic Office, the 

level at the close of the last glacial period. Cores U. S. Coast and Geodetic Survey and the Insti- 

examined during this study support this hy- tute for Oceanography of the Environmental 

pothesis and further indicate that the area now Science Services Administration provided both 

occupied by the strait was a tidal flat or estuarine the oceanographic vessels and funds for this 

environment prior to submergence. study. 

REFERENCES 

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Allison, L. E., 1935, Organic carbon by reduction of chromic acid: Soil Sci., v. 40, p. 311-320. 

Anonymous, 1957, Oceanographic station list, 1957: Marine Res. Indonesia, no. 4, p. 26-29. 

Anonymous, 1963, Observations Oceanographique, Croiseur-Ecole d'Application "Jeanne d'Arc," Cahiers 

Oceanographiques, XV Annee no. 9, p. 666-671. 
Bader, R. G., 1954, Use of factors for converting carbon or nitrogen to total sedimentary organics: Science, v. 

120, p. 709-910. 
Baren, F. A. Van, and Kiel, H., 1950, Contribution to the sedimentary petrology of the Sunda Shelf: Jour. 

Sedimentary Petrology, v. 20, p. 185-213. 
Bemmelen, R. W. Van, 1949, The geology of Indonesia: Vol. I A, General geology of Indonesia and adjacent 

archipelagoes. The Hague, Gov't Printing Office, 732 p. 
Bradley, W. F., 1953, Analysis of mixed-layer clay mineral structures: Analytical Chem., v. 25, no. 5, p. 727- 

730. 
Brindley, G. W., 1961, Chlorite minerals, in The X-ray Identification and Crystal Structures of Clay Min- 
erals: Brown, G, ed., Mineralogical Society, London, p. 242-296. 
Burst, J. F., 1958, Mineral heterogeneity in "glauconite" pellets: Am. Mineralogist, v. 43, p. 481-497. 
Curray, J. R., 1960 Sediments and history of Holocene transgression continental shelf, northwest Gulf of 

Mexico, in Recent Sediments, Northwest Gulf of Mexico: Shepaid, F. P., Phleger, F. B. and Andel, Tj. H. 

van, eds., Am. Assoc. Petroleum Geologists, Tulsa, Okla., p. 221-266. 
Dickerson, R. E., 1941, Molengraaff River: A drowned Pleistocene stream and other Asian evidences bearing 

upon the lowering of sea level during the ice age, in Shifting of Sea Floors and Coast Lines. University of 

Pennsylvania, Bicentennial Conference, University of Pennsylvania Press, Philadelphia, 30 p. 
Emery, K. O., 1960, The sea off Southern California: a modern habitat of petroleum. John Wiley & Sons, 

New York, 366 p. 
Emery, K. O., and Niino, H., 1963, Sediments of the Gulf of Thailand and adjacent continental shelf: Geol. 

Soc. America Bull., v. 74, p. 541-554. 
Ferrell, R. E., 1965, Paleoenvironmental significance of clay minerals in the Shell Creek Shale, Muddy 

Sandstone, and Thermopolis Shale on the East Flank of the Bighorn Mountains, Wyoming, Unpub. M. S. 

Thesis, University of Illinois, 66 p. 
Folk R. L., and Ward, W. C, 1957, Brazos River bar: a study in the significance of Grain size parameters: 

Jour. Sedimentary Petrology, v. 27, p. 3-26. 
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Jour. Geology, v. 32, p. 353-372. 
Goddard, E. N., Trask, P. D., De Ford, R. K, Rove, O. N., Singewai.d, J. T., Jr., andOverbeck, R. M., 

1948, Rock-color chart: Washington, D. C, Nat. Research Council Comm. on Rock-color chart, 6 p. 

(distributed by The Geological Society of America). 
Great Britain Hydrographic Department, 1958, Malacca Strait Pilot, 4th Ed. London, 491 p. 
Griffin, J. J., and Goldberg, E. D., 1963, Clay mineral distributions in the Pacific Ocean, in The Sea: Ideas 

and Observations on Progress in the Seas. Hill, M. N. ed., v. 3, p. 728-741, Interscience Publishers, New 

York. 



SEDIMENTS OF THE MALACCA STRAIT, SOUTHEAST ASIA 127 

Grim, R. E., and Johns, W. D., 1954, Clay mineral investigation of sediments in the northern Gulf of Mexico, 
in Clays and Clay Minerals: Swineford, A., and Plummer, N. V. eds., Nat'l Res. Council Pub. 327, p. 
81-103. 

Guilcher, A., 1963, Estuaries, deltas, shelf, slope, in The Sea: Ideas and Observations on Progress in the Seas: 
Hill, M. N. ed., v. 3., p. 620-654, Interscience Publishers, New York. 

Hantzschel, W., 1939, Tidal flat deposits (Wattenschlick), in Recent Marine Sediments: Trask, P. D. ed., 
Am. Assoc. Petroleum Geologists, Tulsa, Okla, p. 195-206. 

Heezen, B. C, Xesteroff, W. D., Oberlin, A., and Sabatier, G., 1965, Decouverte d'attapulgite dans les 
sediments profonds du golfe dAden et de la mer Rouge: C. R. Acad. Sc. Paris, t. 260, p. 5819-5821. 

Hen wood, A., and Garey, R. M., 1955, A modified technique for the Kjeldahl procedure: Hengar Company, 
Phila., Pa., 4 p. 

Hubert, J. F., 1964, Textural evidence for deposition of many western North Atlantic deep-sea sands by 
ocean-bottom currents rather than turbidity currents: Jour. Geology, v. 72, p. 757-785. 

Inman, D. L., 1952, Measures for describing the size distribution of sediments: Jour Sedimentary Petrology, 
v. 22, p. 125-145. 

Johns, W. D., Grim, R. E., and Bradley, W. F., 1954, Quantitative estimations of clay minerals by diffrac- 
tion methods: Jour. Sedimentary Petrology, v. 24, p. 242-251. 

Kaplan, I. R., and Rittenberg, S. C, 1963, Basin sedimentation and diagenesis, in The Sea: Ideas and 
Observations on Progress in the Seas: Hill, M. N. ed., v. 3, p. 583-619. Interscience Publishers, New York. 

Krempf, A., and Chevey, P., 1934, The continental shelf of PVench Indo-China and the relationship which 
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Krumbein, W. C, and Pettijohn, F. J., 1938, Manual of sedimentary petrography: Appleton-Century- 
Crofts, New York, 549 p. 

Kuenen, PH. H., 1950, Marine Geology: John Wiley & Sons, New York, 568 p. 

Laniz, R. V., Stevens, R. E., and Normon, M. B., 1964, Staining of plagioclase feldspar and other minerals 
with F. D. and C. Red. No. 2: U.S. Geol. Survey Prof. Paper 501-B, p. B152-B153. 

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Niino, H., and Emery, K. O., 1961, Sediments of shallow portions of East China Sea and South China Sea: 
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Council, 9th Session Proceedings, Section II (1961), p. 1-6. 

Shepard, F. P., 1960, Rise of sea level along northwest Gulf of Mexico, in Recent Sediments, Northwest Gulf 
of Mexico: Shepard, F. P., Phleger, F. B., and Andel, Tj. H. van, eds., Amer. Assoc, of Petroleum Geolo- 
gists, Tulsa, Okla., p. 338-344. 

Shepard, F. P., Emery, K. O., and Gould, H. R., 1949, Distribution of sediments on East Asiatic continental 
shelf: Univ. of Southern Calif., Allan Hancock Found., Occasional paper 9, 64 p. 

Smit Sibinga, G. L., 1952, Interference of glacial eustasy with crustal movements and rhythmic sedimentation 
in Java and Sumatra: Geol. en Mijnb., New series, v. 14, p. 220-226. 

Soeriaatmadja, R. E., 1956, Surface salinities in the Strait of Malacca: Marine Res. Indonesia, no. 2, p. 27-48. 

Straaten, L. M. J. V. Van, 1963, Aspects of the Holocene sedimentation in the Netherlands: Verhand. Kon. 
Ned. Geol. Mijnb. Gen., Geol. Ser., v. 21, p. 149-172. 

Sumner, F. B., Louderback, G. D., Schmitt, W. L., and Johnson, C. E., 1914, A report upon the physical 
conditions in San Francisco Bay, based upon the operations of the United States Fisheries Steamer "Alba- 
tross" 1912-1913: Univ. of California Publ. Zool., v. 14, p. 1-198. 

Trask, P. D., 1932, Origin and environment of source sediments of petroleum: Gulf Publ. Co., Houston, 323 p. 

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United Nations Economic Commission for Asia and the Far East, 1961, Geological map of Asia and the 
Far East: Calcutta, India, 6 sheets. 

U. S. Navy Hvdrographic Office, 1944, Atlas of surface currents, Indian Ocean: Hydrographic Office Pub- 
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U. S. Navy Hydrographic Office, 1945, Currents in the South China, Java, Celebes, and Sulu Seas: Hydro- 
graphic Office Publication No. 236, Washington, 14 p. 

U. S. Navy Hydrographic Office, 1951, Sailing directions for the Malacca Strait and Sumatra, 4th ed.: 
Hydrographic Office Publication No. 70, Washington, 485 p. 

U. S. Navy Hydrographic Office, 1955, Instruction manual for oceanographic observations: Hydrographic 
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'S Gravenhage-Alegemeene Landsdrukkerij, 252 p. 

Weaver, C. F., 1958, The effects and geological significance of potsasium "fixation" by expandable clay min- 
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861. 

Wyrtki, K, 1957, Precipitation evapoiation, and energy exchange on the surface of the southeast Asian 
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1961, Naga Report v. 2: The University of California, Scripps Institution of Oceanography, La Jolla, 

195 p. 



Reprinted from JOURNAL OF PALEONTOLOGY Vol. kl, No. 6 
The Society of Economic Paleontologists and Mineralogists 



21 



SOME SPUMELLARIAN RADIOLARIA FROM THE JAVA, PHILIPPINE, 

AND MARIANA TRENCHES 

HSIN-YI LING and WILLIAM A. ANIKOUCHINE 

University of Washington, Seattle 



Abstract — Eight species belonging to five genera of patagium-bearing and morphologically 
closely related spumellarian Radiolaria were found in three sediment cores from the Java, 
Philippine, and Mariana Trenches in the I ndo- Pacific region. These various forms are illus- 
trated and discussed with special emphasis on their intraspecific variation in the degree of 
patagium development or preservation. 



INTRODUCTION 

IN 1964, while returning from the International 
Indian Ocean Expedition, the USC&GS 
Pioneer collected sediment cores from three 
trenches in the Indo-Pacific region (Text-fig. 1). 
The core locations are (names approved by the 
United States Board on Geographic Names) : 

Java Trench, lat 6°00' S., long 101°17' E. ; water 

depth, 3,380 m. 
Philippine Trench, lat 5°25' N., long 127°40' 

E. ; water depth, 8,010 m. 
Mariana Trench, lat 11°18' N., long 141°57' 

E.; water depth, 10,170 m. 



During the preliminary examination of the 
core samples, the presence of uncommonly rich 
radiolarian faunas and abundant fragments of a 
diatom, Ethmodiscus rex (Rattray) Hendey, 
were noticed. Some Radiolaria in the assemblage 
possess highly diversified degrees of patagium. 

In a previous paper, Ling (1966) pointed out 
an inconsistent degree of patagium found in some 
spumellarian Radiolaria genera and discussed in 
detail its relationship to ontogenetic develop- 
ment and taxonomy. At that time, his observa- 
tion was based only on the radiolarian assem- 
blage in bottom sediments from the northeast 
Pacific Ocean. The finding of a similar feature in 



20° 



100° E 



20° 




100° E 



Text-fig. / — Geographic locations of three trench cores from the Indo-Pacific region: 33, Java Trench; 35, 
Mindanao Trench; 36, Mariana Trench; A — Ehrenberg (1861a), location of Enhreberg's sample from the 
Philippine Sea. 

1481 



1482 



HSIN-YI LING AND WILLIAM A. ANIKOUCHINE 




50 



- 100 

X 



o 
o 



150 



200 



250 «" 



JAVA TRENCH CORE 



] LUTITE 
FS| SILTY STREAKS 



- ABSENT 

+ PRESENT (SINGLE SPECIMEN) 

r RARE (2-5 SPECIMENS) 

f FREQUENT (6-10 SPECIMENS) 

C COMMON (11-25 SPECIMENS) 

Q ABUNDANT FRAGMENTS 



Text-fig. 2 — Distribution of some Radiolaria in the 
Java Trench core. 

the samples from the Indo-Pacific region fur- 
nishes additional evidence that such variation in 
degree of patagium seems to be neither a rare 
phenomenon nor biogeographically significant. 
In the present investigation, only those pata- 
gium-bearing Radiolaria and the forms that are 
morphologically closely related are treated. 

ACKNOWLEDGMENTS 

The authors are indebted to Captain Harold J. 
Seaborg, Seattle Regional Office, U.S. Coast and 
Geodetic Survey, and Mr. Ted V. Ryan, Pacific 
Oceanographic Laboratory, Environmental Sci- 
ence Services Administration, Seattle, Washing- 
ton, for their kind permission to use samples 
from the trench-sediment cores for the present 
study. Special thanks are due Mr. Frederick J. 
Collier, Smithsonian Institution, for kindly ar- 
ranging the loan of Martin's (1904) type speci- 
mens, and to Mr. William R. Riedel, Scripps 
Institution of Oceanography, University of 
California at San Diego, and Dr. Catherine Anne 
Clark Nigrini, Department of Geology, North- 
western University, for their constructive advice 
and critical reading of the manuscript. The 

Plates 189 & 190 
are transposed. 



authors, however, bear the sole responsibility 
for the contents of the paper. 

Technical assistance received from Mr. 
Donald R. Doyle and Mrs. Shirley J. Patterson 
during the preparation of the manuscript was 
most helpful. 

The investigation was supported financially 
by Office of Naval Research contract Nonr 477 
(37), project NR 083 012, and National Science 
Foundation grant GA-297. The latter grant also 
allowed the senior author to examine the radio- 




100 



150 



200 



250 



300 



350 



400 



450 



PHILIPPINE TRENCH CORE 



□ 


LUTITE 






|Oc=>0| 


MUD LUMPS 


- 


ABSENT 


H 


SILTY STREAKS 


+ 
r 


PRESENT (SINGLE SPECIMEN) 
RARE (2-5 SPECIMENS) 


tM 


DIATOM 


C 


COMMON (11-25 SPECIMENS) 


S 


WOOD FRAGMENTS 


a 


ABUNDANT FRAGMENTS 



Text-Fig. 3 — Distribution of some Radiolaria in the 
Philippine Trench core. 



SPUM ELLA MAN RADIOL ART A FROM THE INDO-PACIFIC 



1483 



larian specimens deposited at the Museum of 
Paleontology, University of California, Berkeley, 
and at the United States National Museum, 
Washington, D.C. 

This is Contribution no. 403 from the Depart- 
ment of Oceanography and Contribution no. 3 
from the Joint Oceanographic Research Group, 
University of Washington, Seattle. 

LITHOLOGY 

The detailed account on the lithology of the 
core sediments has already been presented 
(Anikouchine& Ling, in press). Therefore, only a 
brief description is given here. The positions of 
the samples studied in these cores are shown in 
Text-figures 2 to 4. 

The Java Trench core contains olive-gray to 
greenish-gray clayey silt interbedded with silt 
layers about 1 cm. thick and consisting of finely 
divided mica. The silt layers are spaced about 
every 25 cm. throughout the core. Cross bedding 
was observed at several horizons in the core. The 
otherwise uniform clayey silt is streaked and 
banded olive brown, moderate yellowish brown, 
dark yellowish brown, and lighter and darker 
grayish green. 

The Philippine Trench core also contains an 
alternating series of sediments. Dark greenish- 
gray clayey silt or uniform texture in layers 2 to 
8 cm. thick are randomly intercalated with 
similarly colored irregular layers, lenses, and 




cr 
o 

o 



50 



100 



150 



1ARIANA TRENCH CORE 



] LUTITE 
HH MUD LUMPS 
F?i SILTY STREAKS 



- ABSENT 

+ PRESENT (SINGLE SPECIMEN) 

r RARE (2-5 SPECIMENS) 



Text fig. 4 — Distribution of some Radiolaria in the 
Mariana Trench core. 



streaks of rough-textured clayey silt that is rich 
in diatom valves in most samples and rich in clay 
lumps in other samples. These layers and lenses 
range in thickness from 5 mm. to 13 cm. and are 
similarly variable in color. The core contains an 
abundance of carbonaceous smears, pyrite 
nodules, and wood fragments. 

It is likely that both the Java and the Philip- 
pine Trench cores represent pelagic sedimenta- 
tion punctuated with accumulations from tur- 
bidity flows. Silt-sized mica is the turbidity-flow 
contribution in the Java Trench, whereas in the 
Philippine Trench diatom valves and, to a lesser 
degree, terrestrial sediments and clay lumps are 
probably contributed by turbidity flows. 

In contrast, the Mariana Trench core has a much 
more uniform composition of light and dark 
yellowish-brown clayey silt, except for some scat- 
tered intercalations of silty layers of a few milli- 
meters thick and layers up to 40 cm. thick con- 
taining clay lumps. The clay lumps contain less 
silt than does the surrounding sediment and 
were probably introduced into the trench from 
areas outside. The mineralogy of the silty layers 
is that of a graywacke — rock fragments, quartz, 
feldspar, serpentine, biotite, and a variety of 
accessory minerals — and thus is indicative of 
sudden changes in sedimentation. The layers 
probably represent the winnowed remains of a 
quantity of sediment that was suddenly intro- 
duced to the ocean bottom from a continental 
source. In this sense, the three trench cores show 
that a similar mechanism of sedimentation 
operates in these trenches. The differences ob- 
served in the cores probably reflect closeness to 
source of sediment and nature of the provenance. 

The authors should like to emphasize the 
following concerning the presence of ooze of the 
diatom Ethmodiscus rex (Rattray) Hendey in 
these three trench cores — for further discussion 
of this subject, see Anikouchine & Ling, in press: 
First, the three studied cores are located within 
or approximately within the biogeographic dis- 
tribution region of this diatom (Semina, 1959, 
fig. 1), yet the diatom is completely absent from 
the top or the uppermost samples of the cores. 
Second, the distribution of this diatom ooze in 
the cores is quite erratic; the ooze is frequently 
found in the middle part of Philippine Trench 
sediments, between depths of 75 and 328 cm. 
from the sediment surface, but is rare in Java 
Trench samples and is completely absent from 
the Mariana Trench subsurface section. 

SYSTEMATIC PALEONTOLOGY 

After the grain-size analysis was made, it was 
found that most of the radiolarian specimens are 
quite free from detritus or organic substances. 



1484 



HSIN-YI LING AND WILLIAM A. ANIKOUCHINE 



Thus, no further chemical treatment was neces- 
sary. The specimens were picked up under a low- 
power stereomicroscope and both single-speci- 
men and strewn slides were made with Canada 
balsam. 

In the tables of measurements, the location of 
the illustrated specimen is recorded in the follow- 
ing way: The first two numerals in the codes, (for 
example, 33-250) refer to the cores and corre- 
spond to the suffix of the core serial numbers 
(for example, PI-442-64-33) assigned at the 
Pacific Oceanographic Laboratory. The number 
33 signifies the Java, 35 the Philippine, and 36 the 
Mariana Trench cores. The following numerals 
indicate the position of the sample in the core, 
that is, the depth in centimeters below the 
surface sediments. If the specimen is in a strewn 
slide, its location is next recorded with the aid of 
the England finder (Riedel & Foreman, 1961). 
During the present investigation, the finder was 
always placed on the mechanical stage of a Zeiss 
photomicroscope in such a way that grid A 1 
was located at the upper left-hand corner. Text- 
figure 5 illustrates the measurements (W, \V, 
L, L') made on the specimens. All the slides will 



be deposited permanently in the Micropaleon- 
tology Collection at the Department of Ocean- 
ography, University of Washington, Seattle, 
Washington. 

Genus Euchitonia Ehrenberg, 1861 

Euchitonia furcata Ehrenberg 

Pis. 189, 190, figs. 1-2,5-7 

Euchitonia furcata Ehrenberg, 1861a, p. 767; . 

18616, ibid., p. 823; 1873a, p. 308; ; 18736, 

p. 288-289, PI, 6 (III), fig. 6; Haeckel, 1887, 
p. 532-533. 

Euchitonia midleri Haeckel, 1862, p. 508-510, PI. 
30, figs. 5-10; Stohr, 1880, p. 110, PI. 5, fig. 5; 
Haeckel, 1887, p. 533; Cleve, 1901 (incl. E. 
ypsiloides), p. 1 1 ; Cocco, 1905, p. 11-12 [question- 
able]; Pofofsky, 1912, p. 137-138, Text-fig. 54 
only [52 and 53 questionable]; Clark, p. 81-85, PL 
4, figs. la,b. 

Euchitonia aequipondata Popofsky, 1912, p. 139-140, 
PI. 7, figs. 3,4. 

not Astromma yelvertoni Macdonald, Haeckel, 
1887, p. clxxix (see discussion). 

not Euchitonia midleri Haeckel, Bachmann and 
others, 1963, p. 136, PI. 11, fig. 62. 

Discussion. — The reason for considering E. 
muelleri to be a senior synonym of E. furcata is 
that E. furcata is the first and only nominal 



Explanation of Plate 189 
All figures ca. X159 unless otherwise indicated; bright field. 

Figs. 1,2 — Euchitonia furcata Ehrenberg. /, Sample 35-328; 2, sample 35-267. 
3,4 — E. elcgans Ehrenberg. 3, Sample 33-2; 4, sample 35-328. 

5-7— E. furcata Ehrenberg. 5, Sample 35-138; 6, sample 35-405 (033/1); 7, sample 35-328 (S40/0). 
X,9— E. cf. E. trianglulum (Ehrenberg) 8, Sample 35-300 (J31/0); 9, sample 35-300 (Q36/0), X200. 



Journal of Paleontology, V. 41 Plate 189 



Ling & Anikouchine 







Journal of Paleontology, V. 41 Plate 190 



Ling & Anikouchine 




SPUMELLARIAN RADIOLARIA FROM THE INDO-PACIFIC 



1485 



species of the present genus mentioned by Ehren- 
berg (1861«, p. 767) in a table and again in a 
table (18616, p. 823) as part of an article in 
which he gave the generic diagnosis. In both 
citations, however, the name E. jurcata was ac- 
companied by two asterisks indicating a new 
genus. For new species, only one asterisk was 
given. (See Ehrenberg, 1858, p. 553.) It is true 
that the description and illustration of E. Jurcata 
were given by Ehrenberg (1873o, p. 308; 18736, 
p. 288-289, PI. 6 (III), fig. 6, respectively) later 
than those of E. muelleri by Haeckel (1862, p. 
508-510, PI. 30, figs. 5-10). Because only the spe- 
cies name was mentioned, however, and because 
the two asterisks were included, Ehrenberg's 
action is here presumed to constitute an indica- 
tion as specified in Article 16 (a) (v) of the Inter- 
national Code of Zoological Nomenclature (Stoll 
and others, 1961). Therefore E. jurcata is consid- 
ered to be a valid name and consequently has 
priority over E. muelleri. 

Campbell (1954, p. 86), in his compilation for 
the Treatise on Invertebrate Paleontology, desig- 
nated E. jurcata as the type of the genus and 




Text-fig. 5 — Schematic diagram of patagium-bear- 
ing Radiolaria showing the measurements (in mi- 
crons) made in this paper. W = the maximum width 
of the arm; W' = the minimum width of the arm; 
L = the length of the arm, measured from the pre- 
sumed geometrical center or center of the central 
structure to the distal end of the arm; L' = the 
length of the arm. 



Explanation of Plate 190 
All figures ca. X159 unless otherwise indicated; phase contrast. 

Figs. 1—7 — The same as corresponding figures in Plate 189. 

8,9— E. cf. E. trianguhim (Ehrenberg). 8, Sample 35-300 (N37/1), X200; 9, Sample 35-300 (Q36/0), 
X200. 



1486 



HSIN-YI LING AND WILLIAM A. ANIKOUCHINE 



marked the date 1872 with an asterisk, indicat- 
ing that the species was fixed by the original 
author on the date of the original publication. 
It is clear from the discussion above that the 
valid date of the present species should be 1861. 
Macdonald (1871, p. 226, figs. 1,2) proposed 
and illustrated a new species, Astromma yelver- 
toni, but did not describe it. Haeckel (1887, p. 
clxxix) considered the species to be synonymous 



are found between the two showing a continuous 
variation, and no clear separation is possible. 
Although we cannot completely support Clark's 
(1965, p. 85) view that "the three specimens de- 
scribed by Popofsky (1912) as E. aequipondata 
are apparently only particularly well-developed 
examples [italics ours] of E. mitlleri" (E. furcata 
in this paper), we nevertheless agree here that it 
is best to consider Popofsky's species as E. 









MEASUREMENTS IN 


MICRONS 










Sample 


W 


W 


L 


L' 


Plate 


fig- 


35- 


-328 


33 


75 


265 


190 


189, 


190 


1 


35- 


-267 


30 


63 


210 


185 


189, 


190 


2 


35 


-138 


38 


60 


150 


120 


189, 


190 


5 


35 


-405(033/1) 


40 


85 


155 


125 


189, 


190 


6 


35- 


-328(S40/0) 


30 


50 


140 


120 


189, 


190 


7 



Observed range 



30-50 



50-90 



140-265 



100-190 



based on 20 specimens 



with his species, E. muelleri, but completely 
neglected to mention this in his Challenger text 
because he evaluated Macdonald' s paper as one 
of six listed pieces of " . . . absolutely worthless 
literature, which contains either only long 
known facts or false statements, and may hence 
be entirely neglected with advantage." Whether 
or not Macdonald's publication is worthless is 
not the subject of the present discussion, how- 
ever. Because all the angles between the arms 
of his figure 1 are the same, the specimen can- 
not be classified in the genus Euchitonia, as 
Haeckel presumed, according to the current 
classification. 

Haeckel (1862, p. 508) once considered his E. 
ypsiloides (originally as Histiastrum ypsiloides 
Haeckel, 1861, p. 843) to be a synonym of E. 
muelleri, but in his Challenger report he then 
treated them as separate species. The descrip- 
tion of E. ypsiloides is quite brief and no illustra- 
tion is given; therefore, the authors could not 
reach any conclusion at this time, and the name 
of E. ypsiloides is not included in the synonymy 
above. 

Numerous specimens of E. furcata recovered 
from the trench samples show a wide range of 
variations in the extent of patagium, the size of 
the specimen, and in the form of the arms, par- 
ticularly at the distal end. For example, three 
specimens here illustrated (Pis. 189, 190, figs. 
5-7) are considered as near typical for the pres- 
ent species, whereas another specimen (Pis. 189, 
190, fig. 1) is comparable to Popofsky's new 
form, E. aequipondata (1912, p. 139-140; PI. 7, 
figs. 3,4). Numerous transitional forms, however, 



Euchitonia elegans (Ehrenberg) 
Pis. 189, 190, figs. 3,4 

Pteractis elegans Ehrenberg, 1873a, p. 319; , 

1873b, p. 298-299, PI. 8, fig. 3. 
Euchitonia elegans (Ehrenberg). Haeckel, 1887, 

p. 535; Cleve, 1901, p. 11; P.iedel, 1952, p. 1-18 

(particularly p. 11-12 and 14); Clark, p. 85-88, 

PI. 4, figs. 2a,b; fig. 18. 
Non? Euchitonia elegans (Ehrenberg), Popofsky, 

1912, p. 138-139, text-figs. 55-57, PI. 7, fig. 2. 

Discussion. — Ehrenberg described (1873a, p. 
319) and illustrated (1873b, PI. 8, fig. 3) the 
present species from a bottom sediment 
(18°03'N, 129°11' E; depth, 6,040 m.) in the 
Philippine Sea. Although he added: "cfr. 
Monatsbericht 1860, p. 767." at the end of his 
original description, the name of this species was 
not found on the mentioned page nor on his 
faunal list in the paper, and it is our understand- 
ing that he referred only to the sample. 

His original illustration (1873b) clearly shows 
that the distal end of each of the three arms nar- 
rows to a point, but actually only one arm, an 
odd one, possess a spine at its distal end. We, 
therefore, agree with Popofsky's (1912, p. 138) 
comments that Haeckel (1887, p. 535) misinter- 
preted Ehrenberg's original figure and stated 
that there are terminal spines at the end of the 
arms. However, judging from the illustration and 
particularly his Text-figure 57, which he con- 
sidered as the only mature as well as the complete 
form, it is doubtful that the specimens Popofsky 
found actually belong to E. elegans. 

The extent of patagium found in the trench 
samples ranges from considerably developed, but 
not as complete as Ehrenberg's specimen, to 
entirely absent. 



SPUMELLARIAN RADIOLARIA FROM THE INDO-PACIFIC 



1487 



MEASUREMENTS IN MICRONS 



Sample 


W 


W 


L 


U 




Plate fig. 


33-2 
35-328 


40 
40 


55 
50 


170 
210 


135 
175 




189, 190 3 
189, 190 4 


Observed range 


33-40 


35-55 


165-265 


115-2 


30 


Based on 25 specimens 



Euchitonia cf. E. Triangulum (Ehrenberg) 
Pis. 189, 190, figs. 8,9 

Stylactis triangulnm Ehrenberg, 1873a, p. 320; 

, 1873b, p. 298-299, PI. 8, fig. 9; Stohr, 1880, 

p. 113, PI. 6, fig. 2 
Euchitonia triangulnm (Ehrenberg), Haeckel, 1887, 

p. 533. 

Discussion. — As in the example of E. elegans, 
Ehrenberg (1873a, p. 320; 1873b, p. 298-299) 
twice indicated that the name of the species was 
proposed during the year of 1860. However, the 
search on this account is without success. 

The original figure illustrated by Ehrenberg, 
based on a specimen from the Philippine Sea, has 
a nearly complete patagium, but the nature of 
the arms is completely obscured. Stohr's (1880, 
PI. 6, fig. 2) figure does not show the patagium, 
and he considered the specimen to be a broken 
one. Both figures, however, illustrate clearly 
that E. triangulnm has a relatively large con- 
centric central structure. 

The specimens assigned here to this species, 
despite the stated discrepancies, seem to agree 
in general with the above-mentioned illustrations 
and with the description subsequently given by 
Haeckel (1887, p. 533). 

The intraspecific variations observed during 
the present study are (1) the inconsistency in the 
extent of the patagium and (2) the shape of the 
arms, particularly the distal ends. 

Dictyastrum angulatum by Ehrenberg (1861a, 
p. 767; 1873a, p. 306; 1873b, p. 288-289, PI. 8, fig. 
18), which Haeckel (1887, p. 589, 590) considered 
to be Rhopalodictyum truncatum of Ehrenberg 
(1862, p. 301), closely resembles the E. triangu- 
lum, except that all arms are equidistant and 
the surface is completely spongy. 



Genus Cyclastrum Rust, 1898 

Cyclastrum? sp. 

Pis. 191, 192, figs. 1-2 

Discussion. — The genus Cyclastrum was es- 
tablished by Rust (1898, p. 28, PI. 9, fig. 5) from 
the Jurassic samples from Italy, C. injundibuli- 
forme being both genotypic and monotypic. The 
generic characteristic given by him is: "Die Dis- 
talenden der drei Arme durch einen spongiosen 
Patagialgiirtel verbunden." 

It is important to point out that Campbell's 
(1954, p. 86) diagnosis for this genus is mislead- 
ing, inasmuch as he described the genus as "like 
Chitonastrum but has patagium," whereas for 
Chitonastrum he indicated, "three distally forked 
[italics ours] arms; no patagium." It seems quite 
clear from the description and illustration given 
by Rust that he never intended to include the 
forked-arms form in his genus. 

The two illustrations here show a specimen 
having the complete patagium and a specimen 
having only a partial patagium located only in 
one of the three interbrachial areas. If the 
patagium is completely absent from them, they 
would be classified in different genera, such as 
Dictyastrum cr Rhopalastrum, according to the 
current generally accepted scheme. 

The concentric nature of the central structure 
is clearly shown in our samples, whereas such a 
feature was not mentioned nor illustrated by 
Rust. 

In view of these discussions and the fact that 
Rust's genus is the closest to the forms that can 
be found, the authors tentatively assign them to 
Cyclastrum. 



MEASUREMENTS IN MICRONS 



Sample 


W 


W 


L 


L' 


Plate fig. 


15-300 (J34/0) 
35-300 (N37/1) 
35-300 (Q36/0) 


60 
60 
50 


100 
80 
90 


130 
110 
110 


80 

75 
70 


189 8 

190 8 
189, 190 9 


Observed range 


50-60 


80-110 


110-140 


70-95 


based on 15 specimens 



1488 



HSIN-YI LING AND WILLIAM A. ANIKOUCHINE 



MEASUREMENTS IN MICRONS 



Sample 


W 


W 


L 


L' 


Plate 


fig- 


35-201 (R41/4) 
35-405 (K4 1/0) 


40 

35 


95 
100 


220 
200 


190 
165 


191,192 
191,192 


1 
2 



Genus Hymeniastrum Ehrenberg, 1847 

Hymeniastrum euclidis Haeckel 

Pis. 191, 192, fig. 3 

Hymeniastrum euclidis Haeckel, 1887, p. 531, fig. 13. 
Cleve, 1901, p. 11; Popofsky, 1912, p. 136-137, 
Text-fig. 51. 

Discussion. — On the basis of the fauna from 
bottom sediments of the northeast Pacific 



Ocean, the degree of patagium shown in the 
specimen of the present species and its relation 
to taxonomy and ontogenetic considerations 
have been discussed by Ling (1966). The oc- 
currence of similar phenomena in the trench core 
samples indicates that such variation actually 
occurs beyond any biogeographic limitation and 
quite possibly is a common phenomenon in these 
patagium-bearing Radiolaria. 



MEASUREMENTS IN MICRONS 



Sample 


\V 


W 


L 


V 


Plate fig 


35-227 (J36/0) 
Observed range 


35 
30-40 


85 
75-100 


180 
150-210 


145 
110-175 


191,192 3 
based on 10 specimens 



Explanation of Plate 191 
All figures ca. X159 unless otherwise indicated; bright field. 

Figs. 1,2—Cyclastrum? sp. 1, Sample 35-201 (R41/1); 2, sample 35-405 (K41/0). 
3 — Hymeniastrum euclidis Haeckel. Sample 35-227 (J 36/0). 
4,5—Dictyocoryne sp. 4, Sample 33-29 (N39/3); 5, sample 33-250. 
6 — D. profunda Ehrenberg. Sample 35-267. 
7 — Rhopalodictyum abyssorum Ehrenberg. Sample 36-120 (M42/0), X200. 



Journal of Paleontology, V. 41 Plate 191 



Ling & Anikouchinc 





' • 'w ~*"-'fr?pcff> * ' . :* V» ****** 





Journal of Paleontology, V. 41 Plate 192 



Ling & Anikouchine 






•■•^Bfe,':,. 







SPUMELLARIAN RADIOLARIA FROM THE IN DO-PACIFIC 



14X9 



Genus Dictyocoryne Ehrenberg, 1861 

DlCTYOCORYNE Sp. 

Pis. 191, 192, figs. 4,5 

Discussion. — The rapidly expanded distal half 
and flatly truncated nature of the distal end, 
forming chalice-shaped arms, are quite charac- 
teristic and clearly distinguish this form from 
any other published species. 

Rare specimens observed in the present study 
prevent this from being considered as new. A 
highly variable extent of patagium in this form 
is, nevertheless, clearly demonstrated. The form 
is found only in the Java Trench sediments. 

MEASUREMENTS IN MICRONS 



Sample 



W W L Plate fig. 



33-29 (N39/3) 
33-250 



39 114 156 191,192 
38 120 144 191,192 



Dictyocoryne profunda Ehrenberg 
Pis. 191, 192, fig. 6 

Dictyocoryne profunda Ehrenberg, 1861a, p. 767; 

, 1873a, p. 307; , 1873b, p. 288-289, PI. 7, 

fig. 23; Haeckel, 1887, p. 592; Martin, 1904, p. 
454, PI. 80, figs. 11-13. 



Discussion — The type locality of this species 
is in sediment at a depth of 6,040 m. in the 
Philippine Sea. Ehrenberg (1861a, p. 767) found 
only one specimen in the sample. Two additional 
occurrences of this species were reported by 
Haeckel (1887, p. 592) from his Challenger 
samples: Station 198, 3,930 m. in the Celebes 
Sea, and Station 274, 3,200 m. in the eastern 
central Pacific Ocean. 

Martin (1904, p. 454) noticed considerable in- 
traspecific variation in the specimens and stated 
"it may be seen from the figures that the arms 
are not absolutely equidistant as they are sup- 
posed to always be in this genus." 

Through the kind arrangement of Mr. 
Frederick J. Collier of the Smithsonian Institu- 
tion we were allowed to examine Martin's pre- 
sumed Miocene slides, deposited at the U.S. 
National Museum (USNM). Four specimens are 
identified by Martin as D. profunda, and among 
them three forms figured by him are found in the 
original marked area of the slides. In all cases, 
the measurements calculated from his figures are 
slightly smaller than those measured directly 
under the microscope. The reexamination pre- 
sents the following results: 



Explanation of Plate 192 
All figures and magnification the same as corresponding 
in Plate 191, except phase contrast. 



ligures 



1490 



HSIN-YI LING AND WILLIAM A. ANIKOUCHINE 



Martin (1904) 
PI. 80 


USNM Colin. No. 
and position 


Remarks 


Figure 1 1 


No. 649655 T38/0 


The concentric pattern is present in the patagium cf the specimen 
but is not illustrated in the figure. 


Figure 12 


No. 649656 N38/3 


The concentric nature of the central structure is observed in the 
specimen but is quite obscure in the figure . 


Figure 13 


No. 649657 N38/0 


As illustrated by Martin. 



Not figured 



No. 649673 N40/1 



The patagium in this specimen is completely absent, and only a 
trace of the structure can be detected in interbrachial areas if 
observed carefully. The reason he did not figure the specimen is 
unknown. 



Although Martin (1904) did not mention it in 
his text, his illustrations show clearly that differ- 
ent degrees of patagium are present in his Mio- 
cene materials. Furthermore, it seems quite clear 
that he already had recognized that, as a part of 
a continuous intraspecific variation, the pata- 
gium of this species could be completely absent. 

In the trench core specimens, the extent of 
patagium observed ranges from nearly complete 
to entirely absent. 



von Frattingsdorf N. O.: Geol. Gesell. Wien, Mitt., 

v. 56, pt. 1, p. 117-162, Pis. 1-24. 
Campbell, A. S., 1954, Radiolaria, in Campbell, 

A. S., & Moore, R. C, Protista 3: Lawrence, 

Kansas, Geol. Soc. America and Kansas Univ. 

Press, Treatise on Invertebrate Paleontology, pt. 

D, p. 11-163, figs. 6-86. 
Clark, C. A., 1965, Radiolaria in Recent pelagic 

sediments from the Indian and Atlantic Oceans 

(Ph.D. thesis): Cambridge, England, Cambridge 

Univ., 234 p. 



MEASUREMENTS IN MICRONS 



Sample 



W 



W 



Plate 



fig. 



35-267 
Observed range 



45 
35-50 



85 
80-120 



150 
130-150 



191,192 6 

based on 10 specimens 



Genus Rhopalodictyum Ehrenberg, 1861 

Rhopalodictyum abyssorum Ehrenberg 

Pis. 191, 192, fig. 7 

Rhopalodictyum abvssorum Ehrenberg, 1861a, p. 769; 

, 1873a, p. 319; . p. 298-299, PI. 8, fig. 17; 

Haeckel, 1887, p. 589 

Discussion. — There seems little doubt that 
forms illustrated here belong to the species de- 
scribed and illustrated by Ehrenberg (1873«, p. 
319; 1873b, PI. 8, fig. 17). He found two specimens 
in the sediments from the Philippine Sea. 



Cleve, P. T., 1901, Plankton from the Indian 
Ocean and the Malay Archipelago: K. Sv. Vetensk.- 
Akad., Handl., v. 35, no. 5, p. 1-58, Pis. 1-8. 

Cocco, L., 1904, I Radiolaria fossili del Tripoli di 
Condro (Sicilia): R. Accad. Zelanti, ser. 3 a , v. 3, 
p. 1-14. 

Ehrenberg, C. G., 1847, Ueber die Mikroskopischen 
kieselschaligen Polycystinen als machtige Gebirgs- 
masse von Barbados: K. preuss. Akad. Wiss. Ber- 
lin, Monatsber., p. 40-60. 

, 1858, Ueber die Organischen Lebensformen in 



MEASUREMENTS IN MICRONS 



Sample 


W 


W 


L 


Plate fig. 


36-120 (M42/0) 
Observed range 


50 
40-50 


65 
65-80 


130 
115-145 


191,192 7 
based on 10 specimens 



REFERENCES 

Anikouchine, W. A., & Ling, H. Y., in press, Evi- 
dence for turbidite accumulation in trenches in the 
Indo-Pacific region: Marine Geol. 

Bachmann, A., Papp, A., & Stradner, H., 1963, 
Mikropalaontologische Studien im "Badener Tegel" 



unerwartet grossen Tiefen des Mittel-meeres: 
Ibid., Jahrg. 1857, p. 538-570. 

, 1861a, Ueber die Organischen und unorganischen 

Mischungsverhaltnisse des Meeresgrundes in 19800 
Fuss Tiefe nach Lieut. Brookes Messung: Ibid., 
Jahrg. 1860, p. 765-774. 



SPUMELLARIAN RADIOL ARIA FROM THE INDO-PACIFIC 



1491 



, 1861b, Ueber den Tiefgrund des stillen Oceans 

zwischen Californien und den Sandwich- Inseln aus 
bis 15600' Tiefe nach Lieut. Brooke: Ibid., Jahrg. 
1860, p. 819-833. 

, 1862, Ueber die Tiefgrund- Verhaltnisse des 

Oceans am Eingange der Davisstrasse und bei 
Island: Ibid., Jahrg. 1861, p. 275-315. 

, 1873a, Mikrogeologische Studien als Zusam- 

menfassung seiner Beobachtungen des kleinsten 
Lebens der Meeres-Tiefgrunde aller Zonen und 
dessen geologischen Einfluss: Ibid., Jahrg. 1872, p. 
265-322. 

, 1873b, Mikrogeologische Studien iiber das 

kleinste Leben der Meeres-Tiefgrunde aller Zonen 
und dessen geologischen Einfluss: K. Akad. Wiss. 
Berlin, Abh., Jahrg. 1872, p. 131-399, Pis. 1-12. 

Haeckel, E., 1861, Fernere Abbildungen und Diag- 
nosen neuer Gattungen und Arten von lebenden 
Radiolarien des Mittelmeeres: K. preuss. Akad. 
Wiss. Berlin, Monatsber., Jahrg. 1860, p. 835-845. 

, 1862, Die Radiolarien, eine Monographic: 

Berlin, Georg Reimer, 572 p., 35 pis. 

, 1887, Report on the Radiolaria collected by 

H.M.S. Challenger during the year 1873-1876: Rept. 
Voy. Challenger, Zool., v. 18, clxxxvii + 1893 p., 
140 pis. 

Ling, H. Y., 1966, Notes on patagium in the radiolar- 
ian genera Hymeniastrum and Dictyastrum: Micro- 
paleontology, v. 12, no. 4, p. 489-492, PI. 1. 

Macdonald, J. D., 1871, Examination of deep-sea 
soundings, with remarks on the habit and structure 
of the Polycvstina: Annals Mag. Nat. History, ser. 
4, v. 8, p. 224-226, figs. 1-2. 



Martin, G. C., 1904, Radiolaria: Maryland Geol. 
Survey, Miocene, p. 447-459, PI. 130. 

Popofsky, A., 1912, Die Sphaerellarien des Warm- 
wassergebietes der Deutschen Stidpolar-Expedition 
1901-1903: Deutsche Sudpolar-Exped., v. 13 (Zool. 
v. 5), pt. 2, p. 73-159, Pis. 1-8, 77 text-figs. 

Riedel, W. R., 1952, Tertiary Radiolaria in western 
Pacific sediments: Goteborgs K. Vet. Vitterh. 
Samh. Handl., ser. B, v. 6, no. 3 (Medd. Oceanogr. 
Inst. Goteborg, 19), p. 1-21, Pis. 1, 2. 

Riedel, W. R., & Foreman, H. P., 1961, Type 
specimens of North American Paleozoic Radio- 
laria: Jour. Paleontology, v. 35, p. 628-632, 7 text- 
figs. 

Rust, D., 1898, Neue Beitnige zur Kenntnis der 
fossilen Radiolarien aus Gesteinen des Jura and 
Kreide: Palaeontographica, v. 45, p. 1- 67, Pis. 
1-19. 

Semina, H. J., 1959, The Distribution of the diatom 
Ethmodiscus rex (Wall.) Hendey among the plank- 
ton: Akad. Nauk USSR, Doklady, v.' 124, no. 6, 
p. 1309-1312, 3 figs 

Stohr, E., 1880, Die Radiolarien fauna der Tripoli 
von Grotte Provinz Girgenti in Sicilien: Palaeon- 
tographica, v. 26, p. 69-124, Pis. 1-7. 

Stoi.l, N. E. and others, 1961, International Code 
of Zoological Nomenclature adopted by the XV 
International Congress of Zoology: London, In- 
ternational Trust for Zoological Nomenclature, 
176 p. 



Manuscript received November 7, 1966 



22 

Reprinted from PROCEEDINGS THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2 Oceanography, Tokyo, 1966 



-71- 

VERTICAL CRUSTAL MOVEMENT ASSOCIATED WITH THE 1964 ALASKAN EARTHQUAKE 
R. J. Malloy . Institute for Oceanography, Environmental Science Services Administra- 
tion, Rockville, Maryland, U. S. A. 

Geophysical reconnaissance including gravity, magnetics, seismic reflection pro- 
filing, and hydrography was carried out in the Spring and Summer of 1964 aboard the 
U. S. Coast and Geodetic Survey ship SURVEYOR in the epicentral area of the March 27 
Alaskan earthquake. Portions of the sea floor southwest of Montague Island, Alaska 
wexe calculated to have been uplifted in excess of 50 feet on the basis of these recon- 
naissance data. This, and adjacent areas of tectonic focus were revisited by the 
SURVEYOR during 1965 to conduct combined hydrographic and ocean bottom scanning sonar 
studies. This work was controlled by precision navigation. A conventional echo- 
sounder using a conical 21 KC sound beam was used to collect hydrographic data, and a 
bottom scanning sonor using two fan shaped sound beams of 150 KC and 160 KC covering a 
total of 2400 feet of the bottom was used to yield a pictorial record of the sea floor. 

The submarine extensions of the fresh fault scarps exposed on Montague Island 
were traced to sea a distance of 12 nautical miles by the combination of the two tools. 
Other lineaments brought out by the bottom scanning sonar are interpreted as strata 
ridges and joints. Areas of bedrock outcrop responded to the high frequency sound used 
in the bottom scanner, whereas areas of the sea floor with a fine grained sediment cover 
did not, in general, return geologically meaningful data. Presumably, this contrast 
in performance is a function of the reflection coefficient of these sea floor environ- 
ments and the penetrability of the water by these frequencies. Large sand waves 
recorded by the bottom scanner in the entrance to Cook Inlet showed, upon subsequent 
coring to be composed of a large percentage of very coarse sand and pebbles. 



23 

Reprinted from PROCEEDINGS, THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2 Oceanography, Toyko, 1966 



-75- 

SUBMARINE GEOLOGY OF THE ALEUTIAN ARC, ALASKA 

Richard B. Perry and Haven Nichols . ESSA, Institute for Oceanography, U. S. Department 

of Commerce, Rockville, U. S. A. 

Six new maps show the bathymetry of the Aleutian Arc (170 E. to 160 W. , 50 N. to 
55 N. ) at a scale of 1 : 400, 000 and a contour interval of 50 fathoms. The geologic 
history of this tectonically-act ive area can be inferred from the bathymetry as well as 
from observations of the seismology, sub-bottom acoustic reflections, gravity, geomag- 
netism and island geology. 

The arcuate Aleutian Ridge was formed in originally oceanic crust by magma 
pushing up from below along a line where the northward-moving floor of the Pacific 
Ocean moves under a more stable section of the ocean floor near the continental blocks 
of Asia and North America. The later thrusting-up of Bowers Ridge, which extends 
northward perpendicular to the Aleutian Ridge at approximately 180 longitude, caused 
extensive transverse faulting and rotation of major blocks on the Aleutian Ridge from 
Adak Canyon west to the Near Islands. The formation of relatively recent volcanoes 
along the northern portions of the Aleutian Islands and erosion by glacial ice and 
water have produced many of the land forms that are found down to 200 meters below sea 
level. The Aleutian Terrace and Trench on the south side of the Aleutian Ridge show a 
relatively youthful form that is still being shaped by tectonic forces, while the 
more stable area to the north of the Ridge is an area of thick, flat-lying sediments. 



24 

Reprinted from PROCEEDINGS THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2 Oceanography, Tokyo, 1966 



-70- 

RESULTS FROM A GEOPHYSICAL SURVEY IN THE NORTH-EAST PACIFIC OCEAN 

G. Pe ter, D. Elvers, and 0. Dewald . Office of Oceanography, Environmental Science 

Services Administration, Washington , D. C, U. S. A. 

Data on sea floor topography and the magnetic and gravity fields have been obtained 

2 
through a closely spaced grid network over an area larger than 650,000 km in the North- 
East Pacific Ocean. 

Magnetic anomalies form bands of highs and lows aligned North-Northwest over the 
surveyed area. These bands are disrupted not only by the well known Mendocino fracture 
zone, but by smaller hitherto unreported fracture zones as well. The fracture zones 
revealed by the detailed survey of the ocean floor and those which may be inferred from 
the discontinuities of the magnetic anomaly bands indicate the dominance of an approx- 
imately dast-west fracture pattern of the North-East Pacific Basin. 

The anorialy bands, running nearly perpendicular to the fractures, further complicate 
the tectonic matrix of the area; these still await an adequate explanation as to their 
geological origin. Such an explanation would need to include the lack of correlations 
that have been found between the gravity and magnetic anomalies in the area. 



25 



Reprinted from BULLETIN OF THE SEISMOLOGICAL 
SOCIETY OF AMERICA Vol. 57, No. 2 

AUTOMATED EPICENTER LOCATIONS FROM A 
QUADRIPARTITE ARRAY 

By T. J. Sokolowski and G. R. Miller 

ABSTRACT 

A quadripartite seismic array has been installed on the island of Oahu, Hawaii, 
to supply additional data for the Tsunami Warning System of the USCGS. The 
nuclear explosion LONGSHOT on October 29, 1965, on Amchitka Island served 
in calibrating the epicenter location system. A moving cross-correlation de- 
termined the P wave time delays between the various station pairs. Time delays 
were then used in a least-squares method to obtain azimuth and emergence 
angles. The emergence angle is used with the Jeffreys-Bullen travel-time curve 
to obtain the distance to the source. The emergence angles obtained by using 
the observed station-pair time delays should be corrected to the emergence 
angles obtained by using the station-pair time delays as computed from the 
Jeffreys-Bullen travel-time curve. This comparison will then compensate for the 
anomalies of the Pacific area. With the values for azimuth and distance, one can 
then arrive at an approximate epicenter location for earthquakes of normal 
depth. This method can be used for those situations which require an epicenter 
location within minutes after the earthquake has been recorded. Methods 
developed here are designed for an on-line computer. 

Introduction 

In April 1965, the Coast and Geodetic Survey installed a quadripartite seismic 
array on Oahu, Hawaii. This system consists of four seismic detecting stations and 
a central control system. The four seismic stations are located at a maximum dis- 
tance apart on the island, and in places of minimum background noise. Location 
points for the four seismic stations are: Kaena Pt., Ft. Barrette, Mokapu, and 
Pupukea. The central control system is located at the Honolulu Observatory (see 
Figure 1). Each station is equipped with a short-period vertical, Benioff seismometer 
(35 lb. mass transducer) and a console unit. The operating magnification of the 
seismometers is between 5000 and 15000. The console which accompanies the 
seismometers contains a calibration mechanism, control unit, phototube amplifier, 
frequency modulator, batteries, and a charger. The ground motion detected by the 
seismometer is telemetered via telephone cables as an FM signal to the central 
control system at the Observatory. Figure 2 is a block diagram of the system. 

The central control system consists of three major units; a main console, Develo- 
corder, and a Dynograph recorder. The main console, which is the first unit of the 
central control system, contains discriminators (which remove the telemetry fre- 
quency), control modules, batteries, charger, timing system, power amplifier, power 
supply, and radio. The main console functions as a sensing, directing link, supplying 
both the Dynograph recorder and Develocorder with the seismic signals from the 
distant seismic stations. This link is also used as a check point to any of the major 
components in the system or for calibration of the instruments. 

269 



270 



BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA 



The Develocorder is the second unit of the central control system. It contains 
five enclosed components: recording, processing, film transport, projection, and 
power. The recording component can receive a maximum of 16 channels of seismic 
data in electrical signal form and convert these signals into rotation of mirror 
galvanometers. Light reflected from the mirror galvanometers then exposes the 16 



21° 40' 


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5ERVAT0RY >. ^- \S 

i 






SCALE IN MILES 



158° 10' 



158° 



157° 50 



157° 40 



Fig. 1. Map showing location of quadripartite seismic array and central control system on 

Oahu. 



STATI IN SITES 



HONOLULU OBSERVATORY 



IY1 K A PU 
| S eismometer 



PU PUK EA 
Seismometer 



KAEIMA PT. 



| Seismometer | - 

FT BARRETTE 
| Seismometer ~J- 



Remote 
Console 



Remote 
Console 



Remote 
Console 



Remote 
Console 



Transmission 



Cable 35 km 
Transmission 



Cable 34km 
Transmission 



Cable 34km 
Transmission 



Cable 2 kr 



MAIM 
CONSOLE 



DEVELOCORDER 



DYIMOGRAPH 
R EC0RDER 



Fig. 2. Block diagram of quadripartite array. 

mm film. The processing component, using X-ray chemicals, develops, fixes, and 
washes the exposed film. The film transport component assures a correct recording 
rate in conjunction with the frequency-regulated power supply. Forward or reverse 
film travel can be obtained for viewing or roll storage. The projection component 
then magnifies and focuses the recorded images on a small-view screen approxi- 
mately ten minutes after the earthquake has been sensed at seismic stations. 
The Dynograph recorder, which is the third unit, is a direct writing recorder. Its 



AUTOMATED EPICENTER LOCATIONS 



271 



main function is as a standby unit. This recorder operates only at those times when 
the Develocorder is inoperative for reasons of maintenance or malfunction. 

Time Delays 

Time delays obtained from the six station pairs are used in determining the 
azimuth from the detecting stations to the event. Since the maximum delay from 
any of the pairs is approximately 4 seconds, these delays should then be determined 
as accurately as possible. The recorded LONGSHOT event was digitized with 
intervals of 0.12 second. This included values of the recording both before and after 
the initial onset of the P-phase pulse. The four stations, therefore, gave four sepa- 
rate time series, which we grouped into six station pairs. Figure 3 shows the four- 



FT. BARRETTE 




o 
o 



KAENA PT. 




MOKAPU 



_L 



10 



20 



25 



time (sec) 
Fig. 3. Quadripartite array recording of the LONGSHOT event. 

station recording of the LONGSHOT event. Three methods were applied in attempt- 
ing to obtain the station-pair time delays; first, visual inspection of initial first 
motion; second, moving cross-correlation; and third, Fourier spectrum analysis. In 
general, in the visual inspection method, all four traces of the initial P-motion were 
not well defined. In most cases only two or three of the traces of the initial P-motion 
were well defined. An attempt was then made to obtain the time delays from the six 
station pairs using the phase-change computed from the cross spectrum (Blackmail 
and Tukey, 1959). For each of the six station pairs, the spectrums, coherence, and 
phase were plotted as functions of frequency. In most cases an expected gradual 
phase-change did not occur although the coherence was relatively high. This rapid 
phase-change resulted in inconsistent time delays. Power spectrum, coherence, and 
phase-change plots are shown in Figure 4 for one of the station pairs. The time delay 
was computed using (Blackman and Tukey, 1959) 



272 



BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA 



T K = 



1 



phase- change 



/ L 360 deg. 
where T K is the time delay for the K th station pair, at frequency/. 







180° 

<D 

-180° 
1.0 

<D 
O 

d 

0.5 £ 



frequency (cps) 



frequency (cps) 



Fig. 4. Plot showing power spectrum, coherence, and phase-change for two of the seismic 

stations. 

The moving cross-correlation technique yielded the most accurate and consistent 
time delays between station pairs. A data window was applied to each section of the 
time series. The cross correlation is given by 



Li 



TO i=\ 



Ui+j Vi 



■I, 



-1,0,1, 



•• I 



where : 

Lj is the cross correlation 

Wj is a weighting function 

Ui and iu are the series being cross-correlated 
m is the number of terms in «,- and y t - 
and 

I is the maximum number of lags. 
For each station pair, the maximum positive peaks in the cross-correlation were 
accepted as the representative maximum correlation. Series segments of various 
lengths were used which included at least the first five to six cycles after the onset of 
initial P-motion. Figure 5 shows the cross-correlation of one of the station pairs 
from which the time delay was obtained. 






AUTOMATED EPICENTER LOCATIONS 



273 



1000 



1000 




time (sec) 



Fig. 5. Plot of moving cross-correlation between recordings at two of the seismic stations. 
Maximum positive peak occurs at —0.8 second. 



Azimuth and Distance 

Once the time delays were obtained for all the station pairs, a least-squares com- 
puter program was developed to obtain the azimuth and distance from the net 
stations to the event. The function H which was minimized is given by 



H = £ {Bk - [D K cos (6 - a K ) cos<p]/V}'- 



K = 1, 



6 (1) 



where : 
B K is the observed time delay for the K th station pair 
D K is the distance between the stations of any K th station pair 
d is the azimuth to the event measured clockwise from north at the center of the 

array 
a K is the angle measured clockwise between the K th station pair and the parallel 

through the station with the highest latitude 
<P is the emergence angle 
and 

V is the assumed velocity oi 8.0 km/sec. 
The azimuth obtained from (1) is the result of a scanning process. The scanning- 
process starts at 0° north and computes the 360° of 6 for each value of <p. <p is limited 
from 0° to 90°. The incremental steps are F° for both <p and 6. When a minimum of H 
is found, it steps back F° in both <p and 6 values and then proceeds forward in smaller 
incremental steps. These steps being G°, where G° < F°. The process stops after a 
length of 2F° is computed. Incrementation can be made as small as desired. This 
scanning process is rapid enough so that there would be small gain from a more 
sophisticated procedure. Figure 6 shows a graph of the least-squares values versus 
azimuth for <p = 0. This curve is a smooth curve which has, in this case, one maxi- 
mum and one minimum. Values of H versus <p and 6 yield a smooth surface which 
leads to no difficulty in obtaining a minimum H value. An attempt was made to ob- 
tain the minimum value of H by considering the simultaneous solution of the equa- 
tions dH/dd = and dH/d<p = 0. No simple analytic solution was obtained for 
these equations. 



274 



BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA 



0.6 1- 




180 
azimuth (9) 



360 



Fig. 6. Graph of least-squares solution versus 6 as 6 varies from 0° to 360° for assumed 

emergence angle <p = 0°. 

Arrival times to the net stations from various earthquake sources were computed 
from the Jeffreys-Bullen normal depth travel-time curve. The various time delays 
were then computed by (2) for various distances from each of the station pairs: 



Cm 



— ) D K COS (0 — a K ) 



K = 1. 



,6 (2) 



where : 

C K is the expected J-B time delay for K th station pair for any azimuth m, and 

dA/dt is the reciprocal of slope obtained from J-B travel-time curve ( Jeffreys, 

1962). 

These C K values, for distances from 30° to 95°, substituted into ( 1) relate various 

<p's for this distance range. Figure 7 shows a graph of <p versus distance. The curve is 




60 
distance (degrees) 

Fig. 7. Graph of <p for various distances from Oahu array. Arrival times, computed from 
the Jeffreys-Bullen travel-time curve, were used in the least-squares method to obtain the 
angles. Assumed velocity of 8.0 km/sec. Point <p = 57° was obtained for the LONGSHOT event. 



AUTOMATED EPICENTER LOCATIONS 275 

monotonically increasing and is only applicable to the C K which are computed from 
the Jeffreys-Bullen curve for normal depth. In order to relate these <p's to the net 
system on Oahu, corrections must be applied to account for the travel-time anoma- 
lies. The corrections are obtained in the following manner. Station-pair time delays 
(B K ) may be obtained from the moving cross-correlation technique. These B K , for 
distances from 30° to 95° and various azimuths, substituted into ( 1 ) yield <p's for 
the various distances and azimuths; in general the <p's will differ from those ob- 
tained by the substitution of the C K in ( 1 ) . Applying the corrections ( the difference 
between the B K values and C K values), a final <p, distance curve can be obtained. The 
corrections imply corrections in velocities for various azimuths which deviate from 
the J-B velocities. To be of practical use, many earthquakes must be analyzed to 
obtain <p for distances between 30° and 95° as a function of azimuth. As of the pres- 
ent, only one event has been analyzed from which the methods have been devised. 

Once the azimuth and distance have been obtained, the geocentric coordinates 
can be easily determined from spherical trigonometry. 

Conclusion 

The quadripartite seismic net on Oahu, Hawaii, can be used to rapidly obtain the 
location of an earthquake epicenter. The earthquake must be large enough to be 
recorded by the array and must fall within the P -range. All tsunamigenic earth- 
quakes meet these criteria. Methods developed here are for those situations which 
require a determination of the epicenter within minutes after the earthquake has 
been recorded. A small computer will do this adequately. 

Acknowledgments 

The authors wish to express their thanks to Dr. W. M. Adams and Dr. A. S. Furumoto for 
their constructive criticism of this paper. 

References 

Blackman, R. B. and J. W. Tukey (1959). The Measurement of Power Spectra, Dover Inc., New 

York. 
Jeffreys, H. (1962). The Earth, Fourth ed., Cambridge University Press, London. 

Joint ESSA-U of H Tsunami Research Effort Environmental Science Services Administration 

University of Hawaii 

Honolulu 

Hawaii Institute of Geophysics Contribution No. 168 

Manuscript received October 7, 1966. 



Reprinted from JOURNAL OF GEOPHYSICAL RESEARCH 
Vol. 72, No. lh, The American Geophysical Union 



Journal of Geophysical Research 



Vol. 72, No. 14 



July 15, 1967 



26 



Geologic Structures in the Aftershock Region of 
the 1964 Alaskan Earthquake 1 

Roland von Huene, 2 Richard J. Malloy, 3 George G. Shor, Jr., 4 
and Pierre St.-Amand 2 

Seismic and echo sounder profiles in the aftershock region of the 1964 Alaskan earthquake 
define a pre-existing zone of discontinuous faults in the area of maximum aftershock strain 
release. Steep reverse faults and possibly other types of steep faults occur in the zone; sur- 
face rupture has probably not been continuous along its full length during any Recent earth- 
quake. The fault zone may represent a narrow area of maximum flexure and uplift in the 
broader area deformed during the 1964 earthquake. An anticline at the continental margin 
with local large structural relief was also uplifted during the earthquake. 



Introduction 

After the 1964 Alaskan earthquake three 
organizations made geophysical observations to 
find structures associated with the earthquake 
and also to determine the structure of the con- 
tinental shelf, the Aleutian trench, and the 
deep Gulf of Alaska seafloor. The U. S. Coast 
and Geodetic Survey ship Surveyor made gravi- 
metric, magnetometric, and continuous seismic 
reflection profiles in the summer of 1964 be- 
tween the Hinchinbrook Entrance and the 
Trinity Islands (Figure 1). The gravity and 
magnetic observations have been combined with 
previous observations at sea and with observa- 
tions on land by the U. S. Geological Survey 
and have been reported by Barnes et al. [1966] 
(also Barnes, in preparation). Closely spaced 
seismic profiles immediately surrounding Mon- 
tague Island have been reported by Malloy 
[1964, 1965]; they show a seaward continua- 
tion of the faulting on Montague Island which 
was active during the 1964 earthquake [Plajker, 
1965]. Malloy used a 1,000-joule EG&G-Alpine 
spark sound system aboard the Surveyor; he 
also made a series of profiles across the con- 
tinental shelf (Figure 1). A 20,000-joule Ray- 
flex spark sound system was employed during 






1 Contribution from the Scripps Institution 
of Oceanography, University of California, San 
Diego, California. 

2 Research Department, U. S. Naval Ordnance 
Test Station, China Lake, California 93555. 

3 Institute for Oceanography, ESSA, Silver 
Spring, Maryland 20910. 

4 Scripps Institution of Oceanography, La Jolla, 
California 92152. 



the same summer by Shor and Reimnitz on 
the Scripps Institution of Oceanography ship 
Oconostota. The Scripps profiles (Figure 1) 
extend from the Gulf of Alaska to Kodiak 
Island, where Shor previously had made seismic 
refraction profiles [Shor, 1962, 1965]. The third 
Scripps profile extends past Middleton Island, 
through the Hinchinbrook Entrance, and into 
Prince William Sound; a study of structures 
and post glacial sedimentation of Prince Wil- 
liam Sound has been reported [von Huene et al., 
1967]. 

Scripps also made seismic profiles off the 
Copper River delta [Reimnitz, 1966]. In the 
summer of 1966 von Huene made seven seismic 
profiles across the continental shelf and the 
Aleutian trench, using combined Rayflex and 
EG&G spark sound systems to obtain as much 
as 38,000 joules of energy. A Rayflex signal- 
processing and recording system completed the 
instrumentation. Additional profiles made on 
the continental shelf during this cruise have 
been reported in part [von Huene, 1966] . 

In this paper we summarize and consider 
data, gathered by the U. S. Coast and Geodetic 
Survey, Scripps Institution of Oceanography, 
and the Naval Ordnance Test Station, that bear 
directly on the structure of the continental shelf 
and the 1964 Alaskan earthquake, combining 
the Coast and Geodetic Survey data with those 
reported by von Huene et al. [1966]. 

Nature of Seismic Reflection Data 

Seismic reflection profiling instruments use 
sound sources that are essentially omnidirec- 
tional. The linear receiving hydrophone array 



3649 



3650 



von HUENE, MALLOY, SHOR, AND St.-AMAND 





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AFTERSHOCK REGION OF ALASKAN EARTHQUAKE 



3651 



is normally one to three wavelengths long and 
therefore has some fore-and-aft directivity, but 
none to the sides. Thus strong reflections from 
either side of the ship are received along with 
the reflections from directly below. The result is 
an addition of reflections from the area insoni- 
fied by the seismic source, and especially in 
deeper water failure to record geologic irregu- 
larities of small horizontal extent. 

Another effect to consider in interpreting 
seismic profiler records is the relative inclina- 
tion of planar geologic features. An inclined 
reflector returns energy to the source area only 
by scattering, so that steeply inclined faults, 
bedding, or other acoustic discontinuities may 
not be seen. 

In the records on which this study is based, 
we have considered sharp folding to be the 
result of deeper faulting. No fault planes were 
directly observed in the reflection records. The 
geometry of beds adjacent to faults, as well as 
seafloor scarps, are good fault indicators. Oc- 
casionally faults are represented by 'blank areas 
or by a series of noncoherent reflections. This 
may be caused by severe deformation adjacent 
to and within a fault zone. It is possible that 
many smaller structures were not recognizable 
on the seismic profiler records, and that not 
only the larger tectonic features but also only 
particular types of features were seen. 

The records obtained are of two distinct 
types. The EG&G-Alpine system produced a 
signal rich in higher frequencies, which brought 
out details not seen in the Rayflex records. The 
lower-frequency signals from the Rayflex system 
gave greater penetration, and under some cir- 
cumstances these records showed distinct struc- 
tures far below the first seafloor multiple. In 
general, both types of records were good when 
sea conditions were favorable; under adverse 
conditions the records deteriorated significantly. 
Our information is therefore not uniform in its 
presentation of various geologic features, and 
smaller faults that are clearly recognizable on 
one profile may not be recognized on others. 
The individual interpretation of records some- 
times differed. 

Distribution and Character of Tectonic 
Structures 

The locations of folds and faults found in 
seismic records and bathymetric profiles are 



shown in Figure 1. Bathymetric profiles made 
without concurrent seismic profiles are so indi- 
cated, and the sense of vertical separation 
along faults is determined with less certainty 
where seismic information is absent. Only se- 
lected ship tracks south of Montague Island 
are used in the compilation of Figure 1; more 
detailed information can be found in Malloy 
[1965]. 

Structures that appear to have formed re- 
cently and that may have been active at the 
seafloor during the 1964 earthquake are denoted 
by special symbols in Figure 2. The somewhat 
subjective criteria for judging the recency of a 
fault scarp are a sharp bathymetric expression 
of the structure on the seafloor and the absence 
of erosion or burial. Such judgment was usually 
made from fathograms recorded concurrently 
with the seismic profiles. Activation or rupture 
at the seafloor in 1964 can be demonstrated 
only for the faults on, and adjacent to, Mon- 
tague Island [Malloy, 1964, 1965; Plafker, 
1965]. Because these faults cut hard, well- 
lithified rocks, they cannot be used as general 
examples for the durability of other scarps on 
the seafloor, which all occur in presumably 
soft sediments. Since there are suggestions of 
both rapid and slow scarp destruction, sharp 
bathymetric feaaures were probably formed at 
various times before 1964. 

The sequence of structures in adjacent profiles 
is often similar in the order of occurrence and 
in the configuration of constituent reflections. 
Lines connecting these structures are approxi- 
mately parallel to the regional trend, but such 
lines would imply that structures are generally 
continuous; it is equally possible that many 
small and discontinuous en echelon faults occur. 

Faults on land and the few areas where faults 
are crossed by closely spaced seismic profiles 
comprise the only available basis for judging 
the general length of structures. Condon and 
Cass [1958] and Condon [1965] have mapped 
a number of probable faults in Cretaceous and 
Eocene rocks that extend for 20 km. However, 
only segments of two of these faults were active 
during the 1964 Alaskan earthquake [Plafker, 
1965; Malloy, 1965], and many of these faults 
show no evidence of strong activity since the 
last major glacial recession [von Huene et at., 
1967]. In middle Tertiary strata north of Kayak 
Island, later Tertiary structures are generally 



3652 



von HUENE, MALLOY, SHOR, AND St .-AM AND 



continuous for a few kilometers but are rarely 
continuous for distances longer than 15 km 
[Miller, 1961]. Structures in upper Tertiary 
and Recent strata do not appear to have so 
great an extent as structures in Mesozoic and 
older Tertiary rocks. 

Where structures can be identified with some 
confidence in successive closely spaced seismic 
profiles, they show significant variations along 
strike. The longest continuous fault observed in 
sediments at the seafloor has a 20-km-long 
landward-facing scarp. Sometimes well devel- 
oped faults change character and die out be- 
tween profiles only 4 km apart. One large 
broad fold southwest of Middleton Island 
changes character significantly in an adjacent 
profile made several kilometers away. Continuity 
between structures in adjacent profiles is indi- 
cated in Figures 1 and 2 only where outstand- 
ing similarity or very close profile spacing 
establishes such a continuity with a good degree 
of certainty. It is possible that similar sequences 
of structures on some adjacent profiles may be 
continuous, because structures continuous at 
depth may deform only short segments of the 
shallow strata clearly displayed in the seismic 
records. The present evidence suggests a few 
long tectonic features and many relatively short 
ones, but a much more detailed survey would 
be required to establish the length and strike of 
individual faults and folds. 

Where the strike of structures can be estab- 
lished, it seems to follow the regional structural 
trend. In Prince William Sound, along Hinchin- 
brook and Montague islands, between Montague 
Island and Kodiak Island, as well as along 
Kodiak Island, tectonic structures appear to 
strike approximately parallel to the continental 
margin and the Aleutian trench (Figure 1). 
Off the Copper River delta, however, where the 
regional trend changes direction fairly rapidly, 
subparallel structures striking nearly east and 
also northeast are separated from each other 
by only short distances, indicating an abrupt 
change in direction rather than a continuity 
of two structural trends. The seismic reflection 
and bathymetric data indicate extreme struc- 
tural complexity in this area, similar to that 
established in the Katella district by Miller 
[1961]. 

Tectonic structures plotted in Figure 1 sug- 
gest a moderately deformed continental shelf. 



What Figure 1 fails to show is the relative size 
of each structure and any differences in age. 
Also, because a greater concentration of data 
occurs in some areas, these areas appear to 
contain the greater number of faults. A few 
critical areas, including the ones off Pt. Elring- 
ton and east of Afognak Island, have little or 
no coverage; however, Plajker [1965] records 
no sharp changes in uplift near Pt. Elrington 
to suggest vertical fault displacement during the 
1964 earthquake. 

The largest structures found are closely 
grouped near the landward ends of most tran- 
sects across the continental shelf. Large struc- 
tures sometimes occur at the edge of the con- 
tinental shelf also. When the positions of the 
structures near land are seen in map view they 
appear roughly aligned parallel to the regional 
trend. Two possible large tectonic features are 
suggested by the assembled information, espe- 
cially when the relative quality of each record 
and other conditions are taken into account: 
(1) a zone of faults, well developed from south- 
ern Montague Island to Portlock Bank, but less 
clearly defined south of Portlock Bank and 
north of Montague Island, and (2) a discon- 
tinuous anticlinal structure with attendant 
faulting at the seaward edge of the continental 
shelf. The locations of these features are indi- 
cated by shaded areas in Figures 2 and 3. 

Selected simplified reflection records (Figure 
3) show how groups of faults are separated 
from the anticlinal structure at the continental 
margin by an area with much less deformation. 
Between southern Montague Island and Port- 
lock Bank there is little doubt that the groups 
of faults belong to a single fault zone. Present 
data suggest that most faults are shorter than 
30 km, the distance between most profiles in 
this area. Along northern Montague Island, 
where seismic transects are not so numerous, 
faulting parallel to the shore was found, espe- 
cially in the Hinchinbrook Entrance (see pro- 
file A, Figure 3). Along northern Hinchinbrook 
Island, Reimnitz [1966] inferred a large fault 
near the shore where there is a steep contact 
between upper Tertiary sediments of the shelf 
and the lithified rocks of the island. Because 
these faults are along the strike of the fault 
zone off southern Montague, they are probably 
an extension of this zone. Some faults of the 
zone cross a platform of the harder rock that 



AFTERSHOCK REGION OF ALASKAN EARTHQUAKE 



3653 




Fig. 2. Map of strain release and tectonic features. Strain release summed in 0.4° radius 
circles. Contours are based on preliminary data from the U. S. Coast and Geodetic Survey 
and are smoothed graphically. Dark shaded area is the zone of faults inferred from marine 
geophysical data. 






projects around southern Montague Island. 
Along Hinchinbrook and Montague islands the 
fault zone separates uplifted lithified and slightly 
metamorphosed rocks of Prince William Sound 
from a subsiding area of younger Tertiary and 
Recent strata on the continental shelf. This 
relation cannot be established from about 25 
km southwest of Montague to just northeast 
of the Kodiak group of islands, because only 
shallow strata are shown clearly in the records, 
but seismic refraction profiles off the northern 
Kodiak Island [Shor, 1965] show the depression 
of the lithified sedimentary rocks under the con- 
tinental shelf. Along Kodiak Island the reflec- 
tion seismic transects are very sparse, but two 
features suggest that a fault zone similar to the 
one along Hinchinbrook and Montague islands 
follows the southeastern Kodiak coast. First, a 
large fault system along the coast separates a 
thick section of upper Tertiary sedimentary 
rocks on its seaward side from the metamor- 
phosed and lithified rocks that make up most 
of the island. Secondly, it appears likely that a 



thick sequence of sediments has accumulated 
on the continental shelf, not only from the re- 
fraction work [Shor, 1965] but also from the 
profile south of Kodiak (Figure 3F), which 
shows strata with an apparent thickness of 
more than 4 km on the shelf. Thus, there is 
evidence of a fault zone that may extend from 
off Hinchinbrook Island southwest partly across 
the platform off southern Montague Island, be- 
coming a well developed series of faults at the 
seafloor from southern Montague to Portlock 
Bank where it again becomes more questionable 
because of sparse data, and then joins the 
Kodiak fault system, possibly extending into 
the Trinity Islands. One edge of the zone may 
come ashore at southern Montague Island and 
also on Kodiak Island, from Narrow Cape south- 
ward along the coast. Although the zone's 
southern terminus is somewhat ambiguous, it 
does not appear in one of the profiles between 
the Trinity and Chirikof islands (Figure 3F). 
The zone's northern terminus is probably in 
the complexly deformed region around the 



3654 



von HUENE, MALLOY, SHOR, AND St.-AMAND 





001 X S83J.3W Hld3Q U31VM 



AFTERSHOCK REGION OF ALASKAN EARTHQUAKE 



3655 



Copper River, where two major structural 
trends intersect. 

Bathymetric expression of the fault zone is 
generally discontinuous and weak. Along the 
coastlines of Hinchinbrook, Montague, and 
Kodiak islands an irregular seafloor suggests 
faulting parallel to the regional tectonic trend, 
but between Montague and Kodiak most bathy- 
metric features trend across the fault zone. 
Some of these are possible glacio-genetic troughs 
trending south and southeast that begin in the 
fiords of the Kenai Peninsula and extend across 
the continental shelf [von Huene, 1966]. How- 
ever, two major bathymetric trends of unde- 
termined origin are athwart the fault zone. The 
first is a large east-west embayment outlined 
by the 100-fathom contour (Figure 1). Closely 
spaced ship tracks and good records establish 
the fault zone through this embayment at a 
point where contours diverge from the embay- 
ment's general trend. The second feature is 
Portlock Bank, where the ship tracks are sparse 
and deep reflections were obscured by multiple 
reflections. A few sharp faults occur along the 
profiles northeast and southwest of the bank. 
The only profile to cross the bank does so 
parallel to the regional trend. It is difficult to 
distinguish tectonic features in the complex 
sequence of poor reflections recorded here. 

Without better control it is not possible to 
establish with certainty whether structures 
strike parallel to the bank's bathymetric trend, 
and whether the fault zone crosses it. Close con- 
touring of bathymetry shows, however, an in- 
flection in the trend of the bank's crestal ridge 
where the fault zone would project across it. 
In PDR profiles of this area a rough bottom is 
indicated. Thus, some evidence on and near the 
seafloor suggests a continuity of the fault zone 
through this feature, but it is probably best to 
consider this continuity with reserve. 

During the earthquake the fault zone did not 
rupture in a single or continuous series of breaks 
at the surface; in some of the transects across 
the zone no surface scarps were found. This 
has probably been true for any earthquake of 
Recent age along it, because in some areas the 
faults are buried by probable glacial and post- 
glacial sediment (Figure 3C; and von Huene 
[1966]). The profiles suggest that faults in the 
zone are discontinuous from 200 to 500 meters 
deep, and thus the fault zone may have behaved 



in the past just as it did in the 1964 earth- 
quake. 

Seismic profiles across the fault zone exhibit 
deformation of Quaternary and possibly upper 
Tertiary strata. The most frequently encoun- 
tered deformational geometry is exemplified by 
Figure 4A. The northwest flank of this structure 
is composed of reflectors whose dip increases 
with depth, indicating progressive continuing 
deformation over a long period of time. Local 
unconformities show that the crest of the fold 
was sometimes elevated to wave base or above 
sea level. The steepest limb of the asymmetric 
fold is always on the southeast side; associated 
fault scarps always face seaward. The structure 
shown in Figure \A changes amplitude signifi- 
cantly in 4 km (profile B, Figure 4). No sharp 
surface expression occurs in profile A (Figure 
4), but a 10-meter scarp on the seafloor is 
found 4 km away in profile B. In general, this 
type of structure appears to have a limited 
extent along strike. Profiles in the fault zone 
frequently cross two or three of these struc- 
tures at relatively close intervals, suggesting 
overlapping shorter faults. 

In no instance have we been able to deter- 
mine by direct observation the fault plane asso- 
ciated with this type of structure ; however, the 
data indicate a 60° to vertical attitude of the 
fault plane. The fold geometry would be diffi- 
cult to produce without a reverse component 
of slip along a steeply dipping fault that is 
inclined landward. 

Parkin [1966] has probably the best evidence 
of strike slip along the fault zone in the re- 
established quadrilateral across the zone be- 
tween Montague and Middleton islands. Middle- 
ton Island appears to have moved southwest 
about 10 meters relative to Montague Island 
and the mainland in the period between 1933 
and 1965. The discontinuous nature of faults 
in the zone suggests strike slip, but discon- 
tinuity is not a feature unique to such faults. 
Although there are indications of a strike com- 
ponent of slip, especially for the 1964 earth- 
quake, it does not appear to be the dominant 
slip component. 

Another type of structure that always has a 
sharp surface expression and a narrower zone 
of deformed reflectors on either side of the fault 
occurs (profiles E and F, Figure 4). It is ex- 
pressed in the records as a sharp fold that must 



3656 



von HUENE, MALLOY, SHOR, AND St.-AMAND 



N W 



SE 




SECONDS 
00 





E 






***] 


5^== 


= ==^— ^ 





VERTICAL EXAGGERATION 
12 X 



VERTICAL EXAGGERATION 
6 X 



Fig. 4. Tracing of reflection seismic profiles across structures in the fault zone and at the 
continental shelf edge. A to C are near 58°50'N latitude and 149° 10' W longitude; B is 6 km 
southwest of A; C is 4 km southwest of B. Inset D was recorded at 57°55'N latitude and 
149°20'W longitude; inset E. at 60°05'N latitude and 146°20'W longitude; and inset F at 
59°35'N latitude and 147°30'W longitude. 



be fault controlled. The scarps, some of which 
have a 40-meter relief, face both northwest and 
southeast, or both landward and seaward. These 
structures are sometimes longer (at least 20 km 
in one instance) and apparently younger than 
the first type, because the deepest strata are 
deformed about as much as the seafloor. In 
other words, the faulting has occurred in a short 
period of time, and no erosion or sedimentation 
has modified the seafloor since faulting occurred. 
The sharp flexure and continuity along strike 
may indicate a thinner sequence of strata 
through which stresses from the basement are 
transmitted to the seafloor. Because they have 
only been found in shallower water, the seismic 
records of these structures are obscured by 
multiple reflections that generally begin 120 
meters below the seafloor. The bedding below 
the multiple is probably, however, also parallel 



to the seafloor, because enough seismic energy 
was used in making some of the profiles to give 
strong reflections from beds below the first sea- 
floor multiple; if inclined beds were present, 
their reflections should have been seen on the 
records as divergent reflections. Since only the 
shallow parts of the records are clear, it is 
difficult to determine the fault plane attitude. 
Both the first and second type of structures 
have approximately the same strike, and they 
are found 10 km or less from each other. It 
may be that both types of structures are pro- 
duced by reverse faults, and that some of these 
fault planes dip seaward. One cannot, however, 
exclude the possibility of shallow normal fault- 
ing ; normal faults are not reported from studies 
on land but occur only 30 km away, near the 
continental margin. The absence of deformation 
in the presumed incompetent strata immedi- 



AFTERSHOCK REGION OF ALASKAN EARTHQUAKE 



3657 



■ately adjacent to the fault plane may be evi- 
dence of extension, but some reverse faults show 
little deformation of adjacent strata. 

Faults with landward or northwest-facing 
scarps are too numerous to be dismissed as 
local variants, but their significance must re- 
main in question until further investigation. 

Relation of the fault zone and the zone of 
maximum aftershock-strain release is shown in 
Figure 2, where strain is represented in terms 
of the equivalent number of magnitude 3.0 
earthquakes, as was done by Allen [Allen et al., 
1965]. Each end of the aftershock strain re- 
lease field has two distinct maxima. The largest 
occurs off Hinchinbrook Island and spreads into 
the area of structural complexity off the Copper 
River. West of this maximum is a smaller one 
which occurs in an area of few data and of no 
known, large, active tectonic feature. At the 
southern end the eastern maximum is near 
Albatross Bank, where an anticlinal structure 
occurs at the continental margin. This sug- 
gests deformation during the earthquake along 
the southern part of the continental margin. 
Other evidence suggests that uplift occurred 
along the continental margin, such as the up- 
lift of Middleton Island [Plafker, 1965] and the 
apparent origin of the tsunami at the edge of 
the continental shelf [Van Born, 1965] ; how- 
ever, significant strain release is indicated only 
at Albatross Bank. 

A linear area of greater strain release be- 
tween these termini corresponds very well to 
the fault zone between Kodiak and Montague 
islands, suggesting that the zone defined here 
was deformed during the earthquake. 

Well developed segments of the fault zone and 
the zone of maximum after-shock-strain release 
are located in the same area where an axis of 
maximum uplift and an axis of most severe 
flexure in the crustal surface may occur [Plafker, 
1965]. The positions of these axes in the uplifted 
area can only be inferred because most of the 
uplifted area is under water. It is reasonable to 
propose that surface rupture and maximum 
flexure are coincident in deforming a homo- 
geneous plate; however, the fault zone existed 
before the 1964 earthquake, and it may have 
been a convenient zone of weakness for surface 
rupture. Although no exclusive case can be 
argued at present, the hypothesis that maximum 
uplift, strain release, surface rupture, and 



flexure occurred along or near the fault zone 
in 1964 is probably the most acceptable at this 
time. 

Profiles A and F (Figure 3) show the con- 
tinental margin structural high. Generally this 
structure is a broad deformed anticline which 
occasionally affects much of the continental 
shelf. Although it is absent in some profiles and 
thus appears to be discontinuous at moderate 
depths, it may be a more continuous feature 
deeper in the section, since a fairly continuous 
gravity high occurs along the whole continental 
margin [Barnes et al., 1966]. 

Discussion and Summary 

The marine data indicate a zone of steep 
faults located where the greatest aftershock 
strain release occurred after the Alaskan earth- 
quake. Surface fault rupture, as well as inferred 
maximum flexure and uplift along this zone, are 
further evidence linking the fault zone and the 
earthquake. The regional tectonic setting and 
the geometry of the fault zone therefore indi- 
cate the type of faults that may have been 
active near the surface in 1964. 

The steep faults suggested by marine data 
are also seen along subaerial parts of the Kodiak 
fault system. Capps [1937] observed that faults 
along the southeast coast of Kodiak Island are 
nearly vertical and are accompanied by local 
severe folding, distortion, and alteration. Moore 
(in Grantz [1964] and personal communica- 
tion) describes the Kodiak fault system as a 
high-angle fault system separating Tertiary 
from metamorphosed Mesozoic rocks with fault 
planes dipping either landward or seaward. On 
southern Montague Island Plafker [1965] (and 
Plafker in preparation, 1967) reports a 55° 
northwest to vertical dip on faults that rup- 
tured at the surface in 1964. Therefore the 
proposed fault zone is expressed (1) by a 
system of faults dipping steeply northwest and 
southeast that separate Tertiary from meta- 
morphosed Mesozoic rocks along Kodiak Island, 
(2) by reverse faults dipping between 60° and 
90° northwest, as well as by southeast-dipping 
faults that deform Recent and probably upper 
Tertiary strata on the seafloor northeast of 
Kodiak Island, (3) by scarps in the hard sedi- 
mentary rocks of the platform around and on 
southern Montague Island, and (4) by de- 
formed Recent strata and by steep faults 



3658 



von HUENE, MALLOY, SHOR, AND St.-AMAND 



separating Recent strata from hard rocks off 
Montague and Hinchinbrook islands. Along 
Hinchinbrook, Montague, and the Kodiak group 
of islands this fault zone occurs at the separa- 
tion of uplifted Mesozoic and lower Tertiary- 
rocks, and a subsiding thick sequence of upper 
Tertiary to Recent sediments. This relation be- 
tween rocks of different age cannot be estab- 
lished between Montague and Kodiak islands but 
at present there is no evidence to suggest that it 
does not occur. Elsewhere in the Prince William 
Sound area the many shear zones that dip 
steeply northwest and southeast are apparently 
inactive [Condon and Cass, 1958; Condon, 
1965; Richter, 1965; von Huene et al., 1967]. 
The marine and land data show that an inter- 
section of two fault systems occurs at the north- 
eastern area deformed by the 1964 earthquake. 
East of Kayak Island and Controller Bay an 
east-west-trending system of faults is dominant, 
and from Hinchinbrook Island to Unimak Pass 
a northeast-trending system is dominant. The 
data at sea do not delineate this intersection 
as clearly as does Condon's mapping in Prince 
William Sound [Condon, 1965], where the 
northwest- and east-west-trending Chugach 
thrust faults apparently terminate the south- 
west-trending Hinchinbrook set of traces. The 
east-west-trending faults are generally exempli- 
fied by the Chugach-St. Elias fault along which 
Mesozoic and older (?) crystalline rocks are 
thrust over Tertiary sedimentary rocks along 
30° to 55° north-dipping fault planes. Appar- 
ently thrust faults characterize the east-west- 
trending system, and steep dipping faults char- 
acterize the northeast-trending system. 

It is important to maintain the distinction 
between these two systems when considering 
deformation accompanying the 1964 earth- 
quake, because an interaction between the two 
fault systems could occur with one system re- 
maining essentially passive. Plafker's contours 
of elevation change swing sharply and extend 
east for 160 km at the northeast end of the 
Kodiak zone, indicating limited and possibly 
passive deformation along the east-west-trend- 
ing system. Press and Jackson [1965] and 
Savage and Hastie [1966] apparently used some 
elevation changes from the east-trending lobe 
of the deformed surface and projected them on 
a plane normal to the northeast-trending fault 
system to approximate the deformation they 



used in applying dislocation theory to model the 
fault plane on which the 1964 earthquake oc- 
curred. Thus, the assumed surface they used 
probably descends too gradually in its southeast 
segment. In a more advanced fault model based 
on dislocation theory, Stauder and Bollinger 
[1966] have used a revised profile determined 
by Plafker across Prince William Sound, which 
is more correct than profiles used in previous 
dislocation theory solutions. 

The deformed surface has been well estab- 
lished by Plafker across Prince William Sound. 
From the maximum uplift along Montague 
Island across 80 km of water to Middleton 
Island, however, there are no available data. 
If deformation during the 1964 earthquake was 
similar to a summation of late Tertiary defor- 
mation, which is one of subsidence, the de- 
formed surface may have subsided seaward of 
Montague Island. Conceivably, the surface 
could bow gradually downward over a mildly 
deformed subsiding area between Montague and 
Middleton islands and then arch again over the 
tectonically active anticline at the shelf edge, 
which rises briefly out of the water at Middle- 
ton Island. The validity of fault models using 
dislocation theory will remain at least as ques- 
tionable as the certainty of the surface of 
deformation seaward of Montague Island. 

Two possible fault planes have been deter- 
mined from the main shock bodywave data 
(Algermissen, 1964, in Plafker [1965] ; Stauder 
and Bollinger [1966]). One fault plane is verti- 
cal or dips 80° southeast, and the auxiliary 
plane is horizontal or dips 10° northwest. 
Whether the earthquake occurred along the 
steep or the gently dipping plane cannot be 
determined from the marine seismic profiles 
because the attitude of the deep zone (prob- 
ably more than 10 km) on which initial de- 
formation occurred is not necessarily the same 
attitude as that of the steep faults in the upper 
1 km of the crust. Press [1965], Plafker [1965], 
Savage and Hastie [1966], and Stauder and 
Bollinger [1966] have discussed the merits of 
both planes. Observations from the work re- 
ported here that are relevant to the Alaskan 
earthquake are as follows : 

1. The discontinuous surface rupture on, and 
south of, Montague Island and the possible 
short seafloor ruptures elsewhere along the fault 



AFTERSHOCK REGION OF ALASKAN EARTHQUAKE 



3659 



zone are probably typical of surface deforma- 
tion during past earthquakes along the zone. 
Parts of the fault zone have little, if any, 
bathymetric expression. This may suggest in- 
frequent events such as the one in 1964 or 
possibly suggest local rapid sediment accumula- 
tion. There is a Tertiary and Quaternary his- 
tory of uplift at the edge of the continental 
shelf, and at least part of this area around 
Middleton Island was elevated during the 1964 
earthquake. 

2. The proposed fault zone contains struc- 
tures of various ages, not all of which may have 
been active in Recent time. In some areas of 
sparse data the continuity of the fault zone is 
not definitely established. Along at least more 
than half of its proposed trace, however, the 
zone occurs between uplifted older highly de- 
formed rock and a probable subsiding area of 
the continental shelf. Thus it is probably an 
important tectonic element of the continental 
shelf. 

3. There is a rather close correspondence in 
location gf the fault zone and the area of maxi- 
mum aftershock-strain release between Mon- 
tague and Kodiak islands. Aftershock-strain 
release is rather evenly distributed around the 
surface trace of the fault zone, suggesting a 
major readjustment of the crustal stress field 
in the volume of rock immediately below its 
surface trace. 

4. Between shore and the continental margin 
is an area that has been subsiding during the 
upper Tertiary. But in models of the causative 
fault based on dislocation theory, uplift of this 
area is inferred. This may cast an element of 
doubt on the basic assumptions for the model, 
but it should be noted that during the earth- 
quake a reversal of the geologic history of net 
uplift in the Kenai and Kodiak mountains 
occurred. 

Probably the most difficult feature to explain, 
if the continent is overriding the ocean basin, 
occurs off the continental margin. It has been 
found (von Huene and Shor [1966], and in* 
preparation, 1967; Hamilton, in preparation, 
1967) that a thick sequence of horizontal strata 
in the Aleutian trench as well as the strata of 
the adjacent abyssal plains, are impressively 
undeformed by compressional folds or faults. 

Acknowledgments. We wish to thank David 



Barnes and Erk Reimnitz for letting us use some 
of their unpublished data. George Plafker and 
George Moore reviewed the manuscript and their 
suggestions greatly improved the paper. 

References 

Allen, C. R., P. St.-Amand, C. F. Richter, and 
J. M. Nordquist, Relationship between seis- 
micity and geologic structure in the southern 
California region, Bull. Seismol. Soc. Am., 55(4), 
753-797, 1965. 

Barnes, David F., W. H. Lucas, E. V. Mace, and 
R. J. Malloy, Reconnaissance gravity and other 
geophysical data from the continental end of 
the Aleutian arc (abstract), Proc. Am. Assoc. 
Petrol. Geol., 1966. 

Capps, S. R., Kodiak and adjacent islands, Alaska, 
U. S. Geol. Surv. Bull, 880C, 111-184, 1937. 

Condon, William H., Map of eastern Prince Wil- 
liam Sound area, Alaska, showing fracture 
traces inferred from aerial photographs, U. S. 
Geol. Surv. Misc. Geol. Investigations Map 
1-458, 1965. 

Condon, William H., and John T. Cass, Map of 
a part of the Prince William Sound area, 
Alaska, showing linear geologic features as 
shown on aerial photographs, U. S. Geol. Sur- 
vey Misc. Geol. Investigations Map 1-278, 1958. 

Grantz, Arthur, in Mineral and Water Resources 
of Alaska, Committee Report, 88th Congress, 
2nd session, p. 59, 1964. 

Malloy, R. J., Crustal uplift southwest of Mon- 
tague Island, Alaska, Science, .7.46(3647), 1048- 
1049, 1964. 

Malloy, R. J., Seafloor upheaval, Geo-Marine 
Tech., 1(6), 22-26, 1965. 

Miller, Don J., Geology of the Katalla District, 
Gulf of Alaska Tertiary Province, Alaska, U. S. 
Geol. Surv. Open File Rept., 1961. 

Parkin, Ernest J., Alaskan surveys to determine 
crustal movement, 2, Horizontal displacement, 
U. S. Coast and Geodetic Surv. Rept., 1966. 

Plafker, George, Tectonic deformation associated 
with the 1964 Alaska earthquake, Science, 
148(3678), 1675-1687, 1965. 

Press, Frank, Displacements, strains, and tilts at 
teleseismic distances, J. Geophys. Res., 70(10), 
2395-2412, 1965. 

Press, Frank, and David Jackson, Alaskan earth- 
quake, 27 March 1964: vertical extent of fault- 
ing and elastic strain energy release, Science, 
147(3660), 867-868, 1965. 

Reimnitz, Erk, Late Quaternary history and sedi- 
mentation of the Copper River delta and vi- 
cinity, Ph.D. dissertation, University of Cali- 
fornia, San Diego, 1966. 

Richter, D. H., Geology and mineral deposits of 
Central Knight Island, Prince William Sound, 
Alaska, Alaska Div. Mines Minerals, Rept. 16, 
1965. 

Savage, J. C, and L. M. Hastie, Surface deforma- 
tion associated with dip-slip faulting, J. Geo- 
phys. Res., 71(20), 4892-4904, 1966. 



3660 von HUENE, MALLOY, SHOR, AND St.-AMAND 

Shor, George G., Jr., Seismic refraction studies off von Huene, Roland, and George G. Shor, Struc- 
the Coast of Alaska 1956-1957, Bull. Seismol. ture of the continental to oceanic transition in 
Soc. Am., 62(1), 37-57, 1962. the Gulf of Alaska, Proceedings oj the 11th Pa- 
Shor, George G., Jr., Structure of the Aleutian cific Sci. Congress, Tokyo, 1966. 
ridge, Aleutian trench, and Bering Sea (ab- von Huene, Roland, George G. Shor, and Erk 
stract), Trans. Am. Geophys. Union, 4^(1), 106, Reimnitz, A geologic interpretation of seismic 
1965. profiles in Prince William Sound, Alaska, Bull. 
Stauder, William, and G. A. Bollinger, The focal Geol. Soc. Am., 78, 4, 1967. 
mechanism of the Alaskan earthquake of March von Huene, Roland, George G. Shor, and Pierre 
28, 1964, and its aftershock sequence, J. Geo- St.-Amand, Active faults and structures of the 
phys. Res., 71 (22), 5283-5296, 1966. continental margin in the 1964 Alaskan after- 
Van Dorn, W. G., Tsunamis, Advan. Hydrosci- shock sequence area (abstract), Trans. Am. 

ence,2, 1-47, 1965. Geophys. Union, 47(1), 176, 1966. 
von Huene, Roland, Glacial marine geology of 
Nuka Bay, Alaska, and the adjacent conti- 
nental shelf, Marine Geology, 4, 4, 1966. (Received December 20, 1966.) 



Reprinted from THE AMERICAN ASSOCIATION OF PETROLEUM 
GEOLOGISTS BULLETIN Vol. 51, No. 9 



27 



ISLAND ARC SYSTEM IN ANDAMAN SEA 1 

L. AUSTIN WEEKS, 2 R. N. HARBISON, 2 and G. PETER 2 

Silver Spring, Maryland 

ABSTRACT 

A sub-bottom profiler survey of the Andaman Sea was conducted as part of the marine geo- 
physical program of the U. S. Coast and Geodetic Survey during the International Indian Ocean 
Expedition. The survey lines were run at right angles to the predominantly north-south tectonic 
lineations of the island arc system. 

A 20,000-joule sparker, energized every 4 sec, was used as a sound source and was towed about 
100 m behind the ship. A 20-hydrophone array received the reflected signals, which were recorded 
both on a paper strip chart and magnetic tape. 

The sub-bottom profiler sections and the marine gravity and magnetic measurements augmented 
knowledge of the geology of the island arc system; the linear structural belts on land were traced 
through the Andaman Sea by geophysical methods. The structural development of the island arc 
system from east to west can be traced, based on available continental and marine data. 

It was possible to delineate the major segments of the island arc system through a distance of 
600 nautical mi (1,110 km) in the Andaman Sea, specifically, the foredeep, outer sedimentary island 
arc, interdeep, inner volcanic arc (and rift valley), and backdeep. 



Introduction 

As part of the International Indian Ocean Expe- 
dition the U. S. Coast and Geodetic Survey ship 
Pioneer conducted continuous sub-bottom profiler 
surveys in the Andaman Sea. These surveys were 
designed to study the nature of the great Indone- 
sian island arc system between Sumatra and 
Burma, and to show the possible interrelations of 
these areas as common members of a single great 
structural geologic province. 

Geologic History and Tectonic Development 

The Indonesian arc developed on the landward 
side of its associated submarine trench, a feature 
which is typical of all arc-shaped island chains. 
For this reason the origin of island arc trenches 
is believed to be closely related to crustal move- 
ment. This view is substantiated further by the 
facts that earthquakes commonly occur along 
trenches, and their foci deepen markedly land- 
ward to depths greater than 200 mi. Volcanoes 
also occur in parallel zones along many of the 
trenches and lie approximately above the zone of 
intermediate-focus earthquakes (landward of the 
trenches). In the Andaman Sea volcanoes are 
present on the landward side of the outer sedi- 
mentary island arc. 

The tectonic development and patterns of the 

'Manuscript received, May 27, 1966; accepted, No- 
vember 18, 1966. 

2 Institute for Oceanography, Environmental Science 
Service Administration; formerly with U. S. Coast 
and Geodetic Survey, Rockville, Maryland. 



Andaman Sea region are discussed in an east-to- 
west direction (Fig. 1). 

The Malay Peninsula is the tectonic continua- 
tion of the eastern Burma north-south fold-moun- 
tain system, which, at the southern end, swings 
eastward, parallel with the island arc system, into 
Borneo. The main fold axes in the southern pen- 
insula trend slightly west of north, changing per- 
ceptibly to east of north at the Thailand-Burma 
border. These structural trends are at an acute 
angle to those of the island arc and are nowhere 
precisely parallel with them. The Mergui Archi- 
pelago along the west coast of Burma is moder- 
ately faulted and has been submerged slightly in 
late geological time (Chhibber, 1934). The Ma- 
lacca Strait and adjoining Sunda Shelf also were 
submerged during Recent time. 

A large fault, striking north-south through cen- 
tral Burma, extends seaward into the Gulf of 
Martaban. In the 1964 Pioneer survey the sub- 
bottom profiler sections did not extend far 
enough east to detect this fault under the Anda- 
man Sea. However, the bathymetry of the eastern 
Andaman Sea shelf and the magnetic observa- 
tions suggest that it is present. Differences in 
structural grain between the Malay Peninsula and 
trends of the island arc on the west could be ex- 
plained by such a fault, downthrown toward the 
west. 

The Malay peninsula came into existence dur- 
ing the Mesozoic as a result of a series of di- 
astrophic cycles during Triassic-Jurassic time. 
The cycles radiated from an older center of 



1803 



1804 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 




Fig. 1. — Map showing major structural trends in Andaman Sea area, southeast Asia. 



ISLAND ARC SYSTEM IN ANDAMAN SEA 



1805 



orogeny on the east (Van Bemmelen, 1949). Evi- 
dence for this Triassic-Jurassic orogeny includes 
the folding of older sediments and intrusions of 
granitic rocks during Triassic-Jurassic time. 

The sedimentary oil-producing basins of Suma- 
tra and Burma (backdeep) are interconnected 
through the Andaman Sea, and are terminated on 
the east by a fault or by the abruptly sloping 
"basement rocks" of the Malay Peninsula. Ac- 
cording to Krishnan (1960) the Andaman Sea 
probably acquired its present shape at the end of 
the Cretaceous. 

West of the peninsula and the backdeep basin 
zone is the Cretaceous folded belt or inner vol- 
canic arc. This belt can be traced from central 
Burma across the Irrawaddy delta, through Nar- 
condam and Barren Islands and Invisible Bank, 
into the volcanic Barisan Range of Sumatra, 
thence through Krakatoa and the Indonesian is- 
lands. The main orogeny, at the end of the Creta- 
ceous, folded and thrusted the pre-Tertiary sedi- 
ments toward the southwest. Uplift and emplace- 
ment of batholiths followed. In Sumatra, the 
whole length of the Barisan Range was elevated 
during the Plio-Pleistocene (Van Bemmelen, 
1949). The Semangko graben (rift) zone de- 
veloped as a post-elevation collapse feature. The 
whole inner volcanic arc comprises a positive 
isostatic anomaly. 

Across an intervening inner sedimentary trough 
or interdeep, the next belt on the west is the non- 
volcanic outer island arc. It can be traced from 
the eastern Himalayan arc southward through east- 
ern India, Burma, the Andaman and Nicobar Is- 
lands, and the islands west of Sumatra. This is a 
Tertiary fold belt, and forms the present-day outer 
island arc. The rocks of this belt are predominantly 
marine sediments which have been folded, faulted, 
and uplifted. The belt is isostatically negative, in- 
dicating a deficiency of mass — in direct contrast 
to the inner volcanic arc. 

West of the outer island arc is the foredeep or 
trench. On the south, this feature is called the 
"Java trench." As a morphological feature the 
trench does not extend north of Simalur Island 
(3°N.), nor is it present off the Andaman and 
Nicobar Islands (Van Bemmelen, 1949). How- 
eveif the 1964 Pioneer survey work indicates that 
the trench is present as a buried structural fea- 
ture off these islands. Vertical and (or) horizon- 
tal movements in the northern part of the Anda- 



mans are believed to have occurred earlier than 
in the southern part. There is a definite gradation 
from coarse to fine sediments in Eocene beds 
from north, to south. Therefore, movements in 
the Andamans and Nicobars are believed to pre- 
date the equivalent belt farther south along the 
Indonesian chain. Westward thrusting of the 
outer island arc geanticline had more or less 
ceased prior to the Miocene — as indicated by 
Miocene sediments that rest unconformably on 
older rocks and are hardly folded (Van Bemme- 
len, 1949). Subsequent elevation of the outer is- 
land arc during the Quaternary has resulted from 
vertical uplift combined with a post-glacial rise in 
sea-level. 

Van Bemmelen (1949), in his classic synthesis 
of the geology of Indonesia, ascribed variations 
along various parts of the same structural belt to 
the fact that different orogenic centers or foci 
were involved. He believed that the Andaman Sea 
belts developed from a different orogenic focus 
than did the areas south and north. Van Bemme- 
len also concluded that northern Sumatra (Atjeh 
section), near which the Pioneer ran several track 
lines, belonged to the same orogenic system as the 
Andaman Sea. 

Sub-Bottom Profiling Results 

Sub-bottom profiling was done along five sec- 
tions that cross the structural belts of the island 
arc system in the Andaman Sea (Fig. 2). Figure 
3 shows sections 1 and 2. Figure 4 shows sections 
3, 4, and 5. Section 5, the southernmost, is 
confined to the backdeep. Section 4, just north of 
Sumatra, extends from the backdeep to the axis 
of the outer island arc. Section 1, a discontinuous 
profile, extends from the backdeep to the fore- 
deep along the Ten Degree Channel just north of 
Car Nicobar Island. Section 3, the northernmost, 
extends from the backdeep in the vicinity of the 
Tenasserim coast of Burma across the submerged 
Irrawaddy delta to a point just south of Preparis 
Island, and then northwest across the outer island 
arc. 

The sections, as interpreted, show form lines of 
the structure and approximate thicknesses of 
sedimentary layers. Some of the faults indicated 
on the sections are clearly observed on the sub- 
bottom profiler records. Others are inferred be- 
cause the attitude of the beds and the structural- 
ly complex geology of the area make their iden- 



1806 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 



ANDAMAN SEA 



15 



10' 



B E 



5° 




Compiled By 



90 c 



95° 



Fig. 2. — Island arc elements of Andaman Sea. Locations of sections 1-S (Figs. 3, 4) shown. Locations of 
Figures 5-8 also can be determined from this figure. 



ISLAND ARC SYSTEM IN ANDAMAN SEA 



1807 



ANDAMAN SEA - SECTION 1 



METERS 
800 

1400 

2400 

3200 

4000 



NW 



284 283 261 260 276 276 274 272 27f 270 



Z£^^FSS?^^- 



269 268 267 266 265 264 263 262 261 260 258 257 256 255 253 252 251 250 248 246 245 




tfl 212 210 208 206 205 204 202 200 199 198 196 195 194 193 192 




METERS 
1600 

2400 

3200 

4000 

4800 



800 
1600 
2400 
3200 



122 120 118 117 116 115 113 112 111 110 109 108 107 106 



FAULT ZONE 



SE 



92 91 


90 


89 


67 66 


85 84 63 








*r* 


\^_^y^^_ 


yOr^V- 




qT 


^7— 


WFv 



NW 



SECTION 2 



SE 



INNER VOLCANIC ARC 




Fig. 3. — Sections 1-2, Andaman Sea island arc system. Locations shown on Figure 2. 



tification less certain. Fault planes and the direc- 
tion of movement along faults commonly are 
indefinite. 

The horizontal scale of the interpreted sections 
is based on the ship's position fixes. These were 
made at 30-min intervals while traveling at a 
speed of about 5 knots. Hence, each fix point 
marked on the sections is separated from the ad- 
jacent fix by a 30-min time interval — regardless 
of the number assigned to it — and the horizontal 
scale is approximately 5 nautical mi between 
every second fix mark. Analysis and interpreta- 



tion of the results preceded the receipt of adjust- 
ed fix locations by many months, but the 
differences between the true or corrected track 
line (as on Fig. 2) and the section track lines 
(Figs. 3, 4) are relatively slight. 

Penetration depths are uncorrected for sound 
velocity. The scale of the sections is based on a 
velocity of 1,600 m/sec, or 5,248 ft/sec. Where 
"lower velocity" sediments overlie or are adja- 
cent to "high-velocity" rocks, any particular ve- 
locity assumption is incorrect. A higher estimated 
velocity would increase the thicknesses of sedi- 



1808 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 



ANDAMAN SEA - SECTION 3 



NW 



41 939 937 935 933 931 929 927 925 923 920 9)9 




SECTION 4 



sw 



620 62 1 622 



626 627 629 630 631 




INNER VOLCANIC ARC 




657 656 659 660 661 662 663 6«4 665 666 667 



669 670 671 672 673 674 675 676 



1600 
2400 



BACKDEEP (EXTENSION OF SUMATRA OIL BASIN) 



=¥ 



3^i 



FAULT ZONE 



SECTION 5 



sw 



20 119 118 117 116 114 112 111 110 109 107 106 105 104 




NE 



1600 
2400 






FAULT ZONE 



Fig. 4. — Sections 3-5, Andaman Sea island arc system. Locations shown on Figure 2. 



ISLAND ARC SYSTEM IN ANDAMAN SEA 



1809 






?•*'<.«£' 5v->;^i£r ,;"'•;;; 



! • ,; ■ w; :•{• 




Fig. 5. — Section 4, fix 639, southwest-northeast profile. Sediments on southwest (left) are seen to 
disappear against hard bedrock or volcanics toward northeast. Mass on northeast is western block of inner 
volcanic arc, supposedly a horst block. A fault is postulated at right side of picture, upthrown toward north- 
east. For location, see Figures 2 and 4. 



merits penetrated, perhaps as much as SO per cent 
in some cases. Bottom depths change greatly 
throughout the Andaman Sea; therefore instru- 
mental scale shifts were frequent. The results of 
the sub-bottom profiler surveys are discussed 
from south to north. 

NORTHERN SUMATRA— SECTIONS 4 AND 5 

The two profiles just north of Sumatra were 
made in order to cross known trends of major 
proportions. Section 4 (Fig. 4) begins on the east 
flank of the outer island arc, which plunges steep- 
ly into the interdeep. Clear evidence of sedimen- 
tation is lacking, possibly because of the rugged- 
ness and steepness of the slope. However, bed- 
ding and some indications of faulting can be seen 
at the top of the arc. Simalur Island, on the 
south, is a geanticline cut by north-south-trending 
transverse faults (Van Bemmelen, 1949). From 
the interdeep to fix 639 several unconformities 
are detectable. Sediments Southwest of fix 639 
(section 4, Fig. 4) disappear against hard bed- 
rock or volcanics on the northeast (Fig. 5). The 
mass on the northeast is the western block of the 
inner volcanic arc — a horst. A fault is postulated 
at fix 639, section 4 (Fig. 4), upthrown toward 
the northeast. 

The part of section 4 from fix 639 to 648 is 



the offshore continuation of the pre-Tertiary and 
lower Tertiary block-mountain system of north- 
ern Sumatra. The block is represented by the 
western side of the Atjeh graben and the islands 
west of the Bengal Passage. There is a lack of 
obvious bedding on the records, probably because 
the rocks are dense. On Sumatra, these rocks are 
primarily Permo-Carboniferous sediments (un- 
doubtedly metamorphosed), diabase, and serpen- 
tinites (Geologic Maps of Netherlands Indies, 
1927). The Atjeh graben, part of the Semangko 
fault zone which can be traced the entire length 
of Sumatra, shows up very clearly. It is consid- 
ered to be a relaxation feature after the Plio- 
Pleistocene uplift in the Barisan (Van Bemmelen, 
1949). On Sumatra the graben is filled with Neo- 
gene (Pliocene and Miocene) sediments which 
are overlain by Quaternary and alluvial deposits, 
and extends into the Bengal Passage. East of the 
graben in northern Sumatra, the rocks are primar- 
ily volcanics (post-lower Tertiary?), identified as 
andesite effusives, or are block-mountain struc- 
tures similar to those on the west side. The whole 
belt from fix 639 to fix 656 represents the inner 
volcanic arc, including the Semangko fault zone. 

Northeast of the inner volcanic arc is the back- 
deep. This is the Andaman Sea extension of the 
Sumatra oil basin. Folding and faulting are evi- 



1810 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 




Fig. 6. — Section 4, fix 671, southwest-northeast profile. Unconformity, showing bottom beds rising toward 
northeast and overlying beds wedging out. Bottom beds reflect one side of an arch whose peak reaches bottom 
surface beyond picture (right). For location, see Figures 2 and 4. 



dent. In this area and also in Sumatra, structural 
complexity tends to decrease away from the inner 
volcanic arc. The zone between fixed 660 and 665 
is more contorted than are zones on the north- 
east. Fixes 665 to 673 are in a broad synclinal 
trough, although the bottom rises gradually to- 



ward the northeast (Fig. 6). Beyond fix 673 and 
northeastward to the large fault at fix 675 (Figs. 
4, 7), sub-bottom reflections disappear (Fig. 6). 
The writers interpret this to mean that the "base- 
ment" or volcanic rocks are faulted against ap- 
proximately 1,600 m of sediments. The fault does 




Fig. 7. — Section 4, fix 675, southwest-northeast profile. Large fault downthrown toward northeast (right). 
Southwestern block consists of "basement" or volcanic rocks faulted against approximately 1,600 m of sedi- 
ments. Note how basal sediments dip into fault, whereas youngest beds drape across fault and onto "basement" 
or volcanic block. Small buried channel can be seen above fault plane, as well as larger buried channel on 
right. For location, see Figures 2 and 4. 



ISLAND ARC SYSTEM IN ANDAMAN SEA 1811 

"■'W^&rB^i . : - ':■ -■■ v* ,,■ ' "• ■'' ^^rn^./'rU '■' J yi "f$W : - ■:"■$■'*'■■ ■.■•"•w-?, 




fklij lli^iU.^'t'^&Tj" il -' .*. *K.U i»L I 



Fig. 8. — Section S, fix 100, northeast-southwest profile. Fault with about 200 m of displacement, down- 
thrown toward southwest (right). About 1,000 m of penetration can be seen here. Fault plane does not quite 
reach ocean floor. For location, see Figures 2 and 4. 



not reach the sea floor, which commonly is the 
case within the areas surveyed in the Andaman 
Sea. Northeast of the fault, the basal sediments 
dip into the fault, whereas the upper beds overlap 
the fault and the "basement" or volcanic rocks. 
The records show an old channel above the fault 
plane; this channel probably was cut into the 
softer materials at that place. 

Section 5 (Fig. 4) is about 50 mi (92 km) 
southeast of section 4. The purpose of this sec- 
tion was to investigate the backdeep, to include 
trends found on section 4, and to search for the 
fault which occurs at the end of section 4 on the 
north (fix 675). The southwestern part of the 
section shows sub-bottom folding and faulting in 
rocks that lie unconformably beneath a thin ve- 
neer of surface deposits. The surface veneer is 
relatively flat, except at fix 118. Between fixes 99 
and 100 a large fault zone was observed (Fig. 8). 
The large fault found on section 4 (fix 675) does 
not appear to be present. A similar relationship 
of "basement" or volcanic rocks to sediments was 
not found on section 5; consequently its extent 
and true significance are not known. 

Northeast of fix 99 the remainder of the back- 
deep shows a folded sub-bottom section, in part 



unconformably overlain by surface deposits. At 
the northeast end of the section, the bottom and 
sub-bottom deposits are conformable and rise 
onto the Andaman Sea shelf. 

TEN DEGREE CHANNEL — SECTION 1 

Section 1 (Fig. 3), the first profile run in the 
area, was interrupted frequently in order to make 
oceanographic observations at various stations. 
Consequently, this profile is not continuous and 
some important features were missed. The sec- 
tion from fixes 245 to 284 includes structural fea- 
tures of the western outer island arc (Nicobar 
Islands), west of the Ten Degree Channel. From 
fix 272 to fix 284, the records indicate sedimenta- 
ry blocks that are thrust westward against the an- 
cient foredeep. The bathymetry west of fix 284 
indicates gradual shoaling. The greatest depths 
are adjacent to the thrust blocks. The Java 
trench (foredeep) terminates considerably south 
of this area and a deep trench does not appear on 
any crossings of the foredeep. However, the 
deepest water is everywhere adjacent to the west- 
ern limit of the outer island arc. It seems proba- 
ble that later sedimentation filled the foredeep 
west of the Andaman and Nicobar Islands. 



1812 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 



From fix 245 to the thrusted blocks at fix 278 
the nature of the western flank of the outer is- 
land arc is evident. The shelf has a rugged and 
youthful appearance, both structurally and topo- 
graphically, which one would expect from an is- 
land mass which has emerged so recently. Bottom 
depth increases approximately 2,400 m between 
fixes 245 and 284, in a distance of 92 nautical mi 
(170 km). 

There is a 16>^-mi gap (31 km) in the record 
between fixes 245 and 212. Both fixes lie in the 
same structural trend along the outer island arc 
and can be considered to be in structurally equiv- 
alent positions. The youthful and structurally 
complex area from fix 192 to fix 212 is the east- 
ern flank of the outer island arc. Bathymetric 
data show its continuation a short distance south- 
east of fix 192. The total width of the outer is- 
land arc in this sector is about 100 mi (185 km). 
The maximum width of Car Nicobar Island, near 
which the Pioneer passed, is 7 mi (13 km). The 
sea-floor base of the outer island arc is many 
times this width. East of the outer island arc the 
bottom is rough and the sub-bottom structure has 
a youthful appearance. Just south of this traverse 
the Nicobar Islands are broken up into several 
groups with trends that apparently extend north- 
ward. 

Fixes 192 and 122 are 30 mi (55 km) apart. 
Sub-bottom profiles were not obtained between 
these fixes, but continuous depth soundings were 
made. 

Bathymetric data indicate that the bottom rises 
markedly to less than 180 m depth just southeast 
of fix 192. The bottom then plunges abruptly to- 
ward the interdeep where depths of about 4,100 
m were observed. It rises again toward the west- 
ern block of the inner volcanic arc west of fix 
120. The bottom of the graben valley (Semangko 
rift) is between fixes 116 and 117 at about 4,800 
m depth. This is deeper than the interdeep by ap- 
proximately 700 m. Lack of sub-bottom penetra- 
tion prevented delimiting the graben valley be- 
tween the faults. Also, the survey line did not 
cross structural trends at right angles. The result 
of this is that the graben has a greater apparent 
width in this section. The peak of the eastern 
block of the inner volcanic arc appears at fixes 
84-86. The western block lies between fixes 120 
and 192, as is the interdeep. The backdeep lies a 
short distance east of fix 83. 



Ritchie's archipelago — section 2 
Section 2 (Fig. 4) was run south of Barren Is- 
land and extends west to Ritchie's Archipelago, 
just east of the Andaman Islands. This section 
and section 4 show very well the structure of the 
inner volcanic arc and associated rift valley. Fix 
680 is above the east flank of the outer island 
arc. The interdeep is evident, with about 800 m 
of sediment in the structural trough. The peak at 
fix 672 lies on the western part of the inner vol- 
canic arc and is approximately half way between 
Invisible Bank and Barren Island. Both the bank 
and the island are part of the inner volcanic arc 
(western flank). The area between fix 672 and 
658 is a continuation of-the Semangko rift valley 
which occurs both on the island of Sumatra and 
offshore (section 4). A large fault may be present 
at fix 660 along the steep slope, but the records 
are inconclusive. Tipper (1911) believes that Bar- 
ren and Narcondam Islands have emerged along a 
master fault zone east of the Andaman Islands. 
However, both Barren and Narcondam Islands, 
as well as Invisible Bank, form only the west side 
of the inner volcanic arc. 

Southeast of fix 658, the profiler and bathymet- 
ric data indicate the presence of another ridge- 
like area. Sediments are more abundant than on 
the flanks of the volcanic arc. Except for a possi- 
ble small intrusive at fix 651, volcanic or base- 
ment-type rocks appear to be lacking. This ridge 
does not extend very far either north or south of 
this section. 

IRRAWADDY DELTA — SECTION 3 

Section 3 (Fig. 4), the northernmost traverse 
made in the Andaman Sea, crossed the submerged 
extension of the Irrawaddy delta from the Tenas- 
serim coast of Burma. Just south of Preparis Is- 
land the east-west traverse was turned northwest 
to its termination. 

The western part of section 3 shows the west- 
ern slope of the outer island arc. At the western 
limit, the slope plunges steeply seaward in the 
foredeep area. Faulting and folding are not no- 
ticeable along the smooth sea floor of this slope. 
A smooth sea floor is typical of the northern tra- 
verse of the Andaman Sea, even where the under- 
lying structure is complex. A small channel at fix 
933 is the only indication of sub-bottom structure 
controlling bottom topography between fixes 923 
and 935. Sub-bottom profiling shows the structur- 



ISLAND ARC SYSTEM IN ANDAMAN SEA 



1813 



al complexity of the wide belt from fix 939 to fix 
909, a distance of 38 mi (70 km). This is the 
outer island arc, whose apex apparently is at fix 
920. East of fix 919 the sub-bottom features are 
even more complex. Here, younger sediments lie 
unconformably on the older folded rocks of the 
outer island arc. Perhaps this is the pre-Miocene 
unconformity, described by Van Bemmelen 
(1949). Thrusting presumably ended before Mio- 
cene time in the outer island arc. The younger 
beds undoubtedly are part of the massive Irra- 
waddy delta. The Irrawaddy River deposits 
670,000 tons of silt per day on its rapidly build- 
ing delta (Chhibber, 1934). Protection from the 
open sea and lack of effective longshore currents 
favor the advance of the delta toward the south. 

Fixes 908 to 888 show the gradual descent of 
the bedrock to the interdeep at about fix 895, and 
gradual rise of the bedrock to the inner volcanic 
arc at fix 888. The deepest or basal reflection is a 
composite, and should not be interpreted as a 
continuous reflection. Single beds cannot be 
traced for long distances. The largest free-air 
gravity value along the entire traverse occurs at 
fix 888 (plus 40 mgals). The extent of the tra- 
verse is covered by deltaic deposits, and lack of 
sub-bottom penetration beneath the bedrock pre- 
vents interpretation of the underlying features. 

East of fix 886 equipment failure prevented 
obtaining data for 16 mi (30 km). Hence it was 
impossible to identify the rift valley (Semangko 
fault zone), which may be buried by overlying 
sediments. The inner volcanic arc does not appear 
to be as well developed here as it is farther south 
(sections 2 and 4). Attenuation of sparker energy 
through the soft overburden masks some fea- 
tures, but the main reason for poor development 
of island arc structure may be that the volcanic 
arc has more mature topography at the northern 
end. There are at least two indications that the 
island arc becomes younger toward the south: 

(1) the infilling of the former trench west of the 
outer island arc to such an extent that it is only 
barely indicated by the bathymetry, even though 
structurally apparent in the sub-bottom; and 

(2) the southward gradation of Eocene sediments 
on the Andaman and Nicobar Islands from 
coarse terrestrial to fine marine (Van Bemmelen, 
1949). 

East of fix 887 the beds appear to dip gently 
east with a few faults. The surface beds lie un- 



conformably on older sediments. Whether all the 
reflections are from delta deposits is uncertain. If 
the basal beds are of deltaic origin, the faults, al- 
though older than the surface sediments, must be 
very recent. Between fixes 857 and 862 an inter- 
esting sub-bottom structure was developed. Its 
interpretation is not clear. The structure may be 
a folder section of the backdeep or the eastern 
segment of the inner volcanic arc, whose twin na- 
ture was noted on the south. Free-air gravity and 
magnetic intensity values increase above this fea- 
ture. Thin surface beds unconformably overlie 
the folded sediments. 

If this folded section is the eastern block of 
the inner volcanic arc, then there is considerable 
divergence of structural trends north from the 
Ritchie's Archipelago traverse (section 2, Fig. 3). 
Off Sumatra and Ritchie's Archipelago, the dis- 
tance between segments is about the same, about 
20 mi (37 km). On the Irrawaddy delta traverse 
the segments may be separated by as much as 61 
mi (113 km), or three times the separation far- 
ther south. However, it appears more likely that 
the eastern segment, if still in existence, is in the 
16-mi (30-km) area of no records between fixes 
876 and 886. 

The remainder or eastern part of the traverse 
has no distinctive features, and contains gently 
folded beds, presumed to be delta deposits. The 
records contain many multiple reflections which 
may mask some structural features. 

Description of Structural Belts 

The study of sub-bottom profiles, bathymetry, 
gravity, and magnetic measurements in the Anda- 
man Sea makes it possible to describe the various 
structural belts of the island arc system. Region- 
ally, these are, from east to west, the following. 

BACKDEEP 

The typical structure of the backdeep is best 
shown in sections 4 and 5 (Fig. 4). In section 3 
(Fig. 4), which also traverses the backdeep, the 
sub-bottom features are masked by the cover of 
deltaic sediments. In general, the structural fea- 
tures of the backdeep are less complex than those 
of the belts on the west, but some large anti- 
clines, synclines, and fault zones are present. The 
largest anticline was recorded off the Sumatra 
coast, between fixes 100 and 105 of section 5. Its 
width is about 14 mi (26 km). This feature could 



1814 



L. AUSTIN WEEKS, R. N. HARBISON, AND G. PETER 



Table I. Similarities of Andaman Sea Inner 

Volcanic Arc and Central Part of 

Mdd- Atlantic Ridge 



A rtdaman Sea Inner 
Volcanic Arc 



Mid-Atlantic Ridge 



Volcanic rock types: serpentine, 
diabase, andesite 

Earthquake belt: zone of epicen- 
ters (200 km) 

Prominent rift valley 

Adjacent high mountains 

Peaks above sea-level: Narcon- 
dam and Barren Islands 

Considerable relief between rift 
valley and adjacent peaks 

Comparable width of rift valley: 
20-25 mi, peak to peak 

Depth to floor of valley ranges 
from 5 000 to 15,000 ft where 
crossed by pro61er 

High length to width ratio 



Volcanic rock types: serpentine, 

diabase, basalt 
Earthquake belt: zone of epicen- 
ters (25 km or less) (G. H. 

Sutton, pers. comm.) 
Prominent rift valley 
Adjacent high mountains 
Peaks above sea-level: Iceland to 

Bouvet Island 
Considerable reliei between rift 

valley and adjacent peaks 
Comparable width of rift valley: 

15-30 mi, peak to peak 
Depth to floor of valley averages 

12,000 ft 

High length to width ratio 



be of impressive size — depending on its extent 
normal to the traverse. Numerous faults were re- 
corded across this anticline, which appears to ter- 
minate against a fault on the northeast, at fix 
100. A smaller anticline is present between fixes 
111 and 115. This feature is about 7 mi (13 km) 
wide and also is faulted. In the backdeep part of 
section 3, two anticlinal structures were observed, 
one \2y 2 mi (23 km) wide between fixes 845 and 
851 and the other 8 mi (15 km) wide between 
fixes 858 and 861. The rocks in both are uncon- 
formably overlain by flat-lying sediments. 

The backdeep consists primarily of sedimenta- 
ry rocks. In most places, the sedimentary sections 
are thicker than 800 m. Suspected volcanic or 
"basement" rocks were found only between fixes 
673 and 675, section 4. The greatest water depths 
at which the backdeep complex was observed 
were at fix 658 of section 4 (about 1,900 m) 
and fix 656 of section 2 (about 2,400 m), both 
adjacent to the inner volcanic arc. 

INNER VOLCANIC ARC AND SEMANGKO RIFT VALLEY 

The inner volcanic arc (with its associated 
Semangko rift valley) was the most interesting 
structural feature observed in the Andaman Sea. 
On land, the rift valley can be traced approxi- 
mately 1,100 mi (2,040 km), the entire length of 
Sumatra. During the 1964 Pioneer cruise, by 
means of sub-bottom profiling, it was traced for 
the first time about 600 mi (1,110 km) farther 
north through the Andaman Sea. Free-air gravity 
values also indicated the presence of the volcanic 
arc beneath the sediments of the Irrawaddy delta 
(Peter et al., 1966), but the sub-bottom structur- 



al detail along the traverse in this area (section 
3) could not be resolved beneath some 400 m of 
sediments. 

The width of the rift valley, as determined by 
the east-west traverses between northern Sumatra 
and Ritchie's Archipelago, is 5-10 mi (9^-18^ 
km) between the bounding ridge crests. The val- 
ley relief, between adjacent ridge crest and valley 
floor, is 1,200 m off Sumatra (section 4) and 
2,000 m at section 2. The western ridge of the 
inner volcanic arc rises higher above the sea floor 
and is a more massive feature than the eastern 
ridge. Narcondam and Barren Islands and Invisi- 
ble Bank are part of the western structural ele- 
ments of the inner arc system. 

The magnetic and gravity results in the Anda- 
man Sea area provide further evidence of the 
submarine continuation of the inner volcanic arc 
(Peter et al., 1966). A broad magnetic high belt 
extends from the tip of Sumatra approximately 
600 mi north to the Irrawaddy delta traverse 
(section 3). This belt broadens northward to 
Narcondam Island and then narrows before it 
crosses section 3. Gravity highs in excess of 50 
mgal occur off the tip of Sumatra and at Invisi- 
ble Bank, Barren Island, and Narcondam Island. 
The largest free-air values, in excess of 100 mgal, 
were observed at Invisible Bank and Barren and 
Narcondam Islands — a value of more than 150 
mgal being present at the south end of Invisible 
Bank. Interesting similarities between the Anda- 
man Sea inner volcanic arc and the Mid-Atlantic 
Ridge are listed in Table I. The Mid-Atlantic 
Ridge is a much longer structural feature and is 
not part of an island arc development, but the 
rift valley and many related tectonic features 
are common to both the Mid-Atlantic Ridge and 
the Andaman Sea inner volcanic arc. 

INTERDEEP 

The interdeep is the structurally depressed belt 
between the two major uplifts of the island arc 
system. Its appearance is similar along the north- 
south extent of the arc except in the extreme 
north where deltaic deposits have masked many 
features. Off Sumatra (section 4) approximately 
700 m of flat-lying sediments fill the depression 
(interdeep) between the two arcs. The eastern 
slope of the outer island arc is steeper than the 
western slope of the inner volcanic arc and may 
have been the source of most of the sediment. On 



ISLAND ARC SYSTEM IN ANDAMAN SEA 



1815 






the south, the interdeep separates Sumatra and 
the offshore Mentawai Islands. The interdeep was 
not profiled in the Ten Degree Channel (section 
1), but is indicated by the bathymetry on several 
other traverses made by the ship. 

Off Ritchie's Archipelago on the east flank of 
the outer island arc in section 2, the narrow and 
downwarped interdeep is filled with sediments 
that appear to have been deposited from both 
flanks and folded in the form of a syncline as the 
downwarping continued. In section 3 off the Irra- 
waddy delta, the broad interdeep lies between 
flanks with very slight slope, and is filled with 
sediments that mask its topographic expression on 
the sea floor. 

OUTER ISLAND ARC 

The outer island arc is composed predominant- 
ly of sedimentary rocks. It is the youngest arc of 
the whole Andaman Sea structural system. It 
continues north of section 3 as the Arakan Yoma 
(mountains) of western Burma and finally abuts 
against the eastern Himalayan arc along the 
Burma-India border. Toward the south, the outer 
arc includes the Mentawai Islands off Sumatra 
and the submarine ridge on the landward side of 
the Java trench. 

The outer arc is structurally complex. It has 
the overall features of a large anticline. Its width 
in places exceeds 100 mi (185 km). Near the Ir- 
rawaddy delta the outer arc narrows before en- 
tering Burma, but toward the south, between 
Narcondam and Barren Islands, a distinct east- 
ward bulge is indicated by the bathymetric data 
obtained by the Pioneer. The sub-bottom profiles 
of sections 1 and 3 suggest that westward thrust- 
ing of the outer arc took place. The apparent 
thrust ridges of section 1 can be traced north- 
ward by means of the bathymetric data. The 
presence of other ridges with long, straight, east- 
dipping slopes suggests westward thrusting. 

Gravity measurements show a negative free-air 
anomaly approximating the peak axis (line of 
highest elevations) of the outer island arc (Peter 
et al., 1966). The peak axis of the arc and the 
negative gravity axis coincide exactly at the south 
end of the index map (Fig. 2). At 8°00' N. and 
93°30' E. the negative gravity axis veers east of 
the Nicobar Islands. It continues east of the islands 



and rejoins the peak axis of the outer islands 
where the negative gravity axis enters Burma. The 
trend labeled "subsidiary or main mass axis" on 
Figure 2 is the negative gravity axis north of 8° 
N. A belt as wide as the outer island arc and 
tilted westward would be expected to have its 
main mass axis lying east of its surface peaks 
(Nicobar and Andaman Islands). The zone of 
westward thrusts on section 3, Ritchie's Archipel- 
ago (southwest of Barren Island), and the clus- 
ter of islands at 8°00' N. and 93°30' E. are con- 
sidered to be parts of the subsidiary trend, coin- 
ciding with the negative free-air anomaly. 

Results of Survey 

The geologic-geophysical investigations of the 
1964 Pioneer Indian Ocean Expedition provided 
much new data and information about the geolog- 
ical features of the Andaman Sea, particularly the 
submarine tectonic patterns and crustal develop- 
ment of the area. The sub-bottom profiles made 
it possible to delineate the major segments of the 
island arc system through a distance of more 
than 600 mi (1,110 km) and provided informa- 
tion about the structural relations of the base- 
ment and overlying rock complexes in the major 
structural belts — foredeep, outer sedimentary is- 
land arc, interdeep, inner volcanic arc and associ- 
ated rift valley, and backdeep. Continued detailed 
analysis of the geophysical data obtained in the 
Andaman Sea area and correlation of the 1964 
results with results of other surveys can be ex- 
pected to yield additional discoveries of scientific 
significance. 

References Cited 

Chhibber, H. L., 1934, The geology of Burma: Lon- 
don, Macmillan and Co., 538 p. 

Geologic Maps of Netherlands Indies, 1927, Scale 
1 :1, 000,000: compiled by J. V. Scrivenor. 

Krishnan, M. S., 1960, Geology of India and Burma, 
4th ed. : Madras, Higginbothams (Private), 604 p. 

Peter, G., L. A. Weeks, and R. E. Burns, 1966, A re- 
connaissance geophysical survey in the Andaman 
Sea and across the Andaman-Nicobar island arc : 
Jour. Geophys. Research, v. 71, no. 2 (Jan.), p. 
495-509. 

Tipper, G. H., 1911, Geology of Andaman Islands, 
with references to Nicobars: Mem. Geol. Survey 
Ind.v. 35, pt. 4, p. 195-213. 

Van Bemmelen, R. W., 1949, Geology of Indonesia, v. 
1A: The Hague, Govt. Printing Office, 732 p. 



28 

ESSA-JTRE-2 



HIG-67-16 



DOUBLE-HUMPED WAVES ON A SLOPING BEACH 



By 
JAMES P. BUTLER 

UH-3SA iOiNT TSUMAMI RESEAJtOf EHOW 
HAWAII WSTITOT! OF CEOfflYSKS 
2525 COBBEA ROAD 
HONOLULU, HAWAII 96822 

AUGUST 1967 



Prepared for 

ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION 

INSTITUTE FOR OCEANOGRAPHY 

JOINT TSUNAMI RESEARCH EFFORT 

with the 
HAWAII INSTITUTE OF GEOPHYSICS 



HAWAII INSTITUTE OF GEOPHYSICS 

UNIVERSITY OF HAWAII 



ESSA 




ESSA-JTRE-2 HIG-67-16 



DOUBLE-HUMPED WAVES ON A SLOPING BEACH 

By 
James P. Butler 



Prepared for 

Environmental Science Services Administration 
Institute for Oceanography 
Joint Tsunami Research Effort 

with the 
Hawaii Institute of Geophysics 

Approved: August 17, 1967 

Chief, Director, 

Joint Tsunami Research Effort Hawaii Institute of Geophysics 



CONTENTS 



Page 



Abstract . 

1. Introduction 

2. Preliminary Equations 

3. Specific Solution . 

4. Propagation of the Wave 

5. A Numerical Example 

6. Acknowledgements 

7. References , 



1 

2 

2 

7 

19 

26 

27 

28 



iii 



ABSTRACT 

The nonlinear shallow water theory in two dimensions has been 
used to compute the behavior of selected wave shapes on sloping beaohes. 
These waves all are initially at rest with two humps of specified 
heights. An analytic solution is found for the behavior of the wave 
height and velocity at the shoreline. Particularly interesting are the 
amplifications of the respective humps 3 when related to the wave shape. 
Numerical techniques are used to find the general behavior of the wave 
off the shoreline. 



-1- 



-2- 

1. INTRODUCTION 

In recent years interest in the behavior of water waves on sloping 
beaches has increased sharply. As is known, however, the conventional 
linearized approach to the study of water waves in the deep ocean is 
invalid in the coastline regions and one must turn to the nonlinear 
theory for treatment of the problem. Some general two-dimensional 
treatments have appeared in the literature (Carrier and Greenspan, 
1958; Carrier, 1965). With a uniform sloping beach, explicit solutions 
exist from which arbitrary wave shapes can be constructed. In this 
paper we consider two-dimensional double -humped wave shapes in the non- 
linear theory and their behavior on the beach. 

2. PRELIMINARY EQUATIONS 

The notation and development given in this section is taken from 
Carrier and Greenspan (1958). The conservation equations in the non- 
linear shallow-water theory are 



[v*(Tf* + h*)]^ = - Tt* t * (1) 



and 



v*.* + v*v* x# = - gTl*^ (2) 



where the asterisks denote dimensional quantities; v* is the 
horizontal velocity, Tl* is the height of the surface above mean sea 
level, h* the height of mean sea level above the bottom, x* the 



-3- 



the horizontal distance with origin at the mean shoreline. For our 
case, we have a uniform sloping beach, or 

h* = - ox* 

where a is the slope of the beach. Following the convention, 
dimensionless quantities are introduced: 

v = v*/v x = x*/A 

t = t*/T T) = T\*/a& 



c 2 = (h* + T\*)/otl 



where 



1 
v = (g£ «)* 



T = (& Q /ctg)' 



and & is a characteristic length for a specific problem. With 
these substitutions, (l) and (2) become 

[vcn - x)] x + \ = o O) 



V t + W x + \ = ° (U) 



-4- 



and the situation applies to a beach of unit slope. By Stoker (19U8), 
these two hyperbolic equations can be transformed into four 
equations in the parametric variables a and P : 



Xp - (v + c)t =0 v p + 2c & + t p = (5,6) 



x - (v - c)t = v - 2c + t = . (7,8) 



From (6) and (8), after integration, we have (noting the convenient 
choice of integration constants): 

v + t = (a - p)/2 (9) 

c ■ (o + p)/U . (10) 

We define two final independent variables a , X as 

X = a - P = 2(v + t) (11) 

a = a + p = Uc (12) 

and (5) and (7) become 



x - vt + ct. = (13) 

a a A. 



*X + Ct a " vt X = ° (lU) 



-5- 



or by eliminating x 



°(\X ~ t oa ) - 3t a = ° • < 15) 



Also, by (11) 



o"K, - v ) - 3v = . (16) 

v XX aa a 



We now introduce a potential $(a,\) such that by definition 

v =^$ a (a,X) , (17) 

and after some manipulation the expressions for the other variables become 



x = $ /k - a 2 / 16 - v 2 /2 (18) 



1) =$,/!+ - v 2 /2 (19) 



t = | - v , (20) 



and $ itself satisfies 



KA - CT *u = • (' 21 > 



-6- 



We now have a linear set of equations in a and X , and T| and v 
are implicit functions of x and t . The shoreline is now the 
line a = . The waves do not break as long as the implicitly- 
defined functions T](x,t) and v(x,t) are single -valued, i.e., 

Ifc4\ ^ for a > 

The solution of (2l) is given by 

$ = AJ (u)ct ) sin(uuX + 6) (22) 

o 

and since equation (2l) for $ is linear, we car superimpose 
solutions as 

CO 

$ = [ dk k A(k) J (ka ) sin(kX + 6) (23) 

J O 

o 

whence 

CO 

= 1$ _ ll [ dk k 2 A(k) J n (ka) sin(kX + 6) . (2U) 

a a a J 1 



v = — $ 



But we will require our boundary conditions to include an initial wave 
shape with zero velocity at zero time. For v = t = , (2) implies 
that X = ; the condition on v is satisfied if in (2k) we set 
6=0. So we have finally 



-7- 



$ = J dk k A(k) J Q (ka) sin(kX) (25) 



where A(k) must be found by the boundary conditions. Now at 
t=0,v=X=0,so Tl and x become: 



Tl(o,0) =1 [dkk 2 A(k) J o (ka) (26) 



x(a,0) = Tl(a,0) - a 2 /l6 . (27) 



From (26) we obtain 

00 

^k A(k) = J da a T)(a,0) J (ko) (28) 

o 

and by specifying 1](x) parametrically in a , one can solve the 
problem (at least in theory). 

3. SPECIFIC SOLUTION 

We now turn our attention to a class of double-humped wave shapes 
given initially by (t = v = 0): 



2 
11(0,0) = ea U (2a - o 2 f e _pa (29) 



x(a,0) = 11(0,0) - a 2 /l6 . (30) 



-8- 



2 
This form was chosen since for small e , x goes like - o and 

T) behaves like ex (a + 8x) e . In this formulation, the 

product (ap) is the critical number. It approximately determines the 

relative heights of the two humps. Crest-spacing can be changed with 

a and also with H for a specific problem. Some examples of T| 

versus a and T\ versus x are shown in Fig. 1. The equation (28) 

has a closed-form expression: 

00 

2 

A*(k) = I k A(k) = e f dao 5 (2a - a 2 ) 2 e~ pa J (ka) 
*+ j o 

o 

= , [b Q + b 2 k 2 + b^ + b 6 k 6 + b 8 k 8 ]e" k2 / U P (3D 

where 



b m -% (12 - 12ap + Ua 2 p 2 ) 
o 5 
P 



b 2 = ^ (- 12 + 9ap - 2a 2 p 2 ) 
P 

2 2 
1^29 , a p x 

P 



b 6 ^(-s + i> 



"8-^9 ' (32) 



-9- 



Now that we have an explicit solution for A(k) , the expressions for 
1) , x , v , and t are all integrals involving this A(k) . For 
0=0 (shoreline) these integrals have closed-form expression. It 
is significant to investigate fully the shoreline characteristics of 
run-up position (amplification) and velocity. For a = , equation 
(2k) becomes 

00 

v = - I J dk k 3 A(k) sin k\ 

o 

CD 

= - 2 J dk k 2 A*(k) sin kX 
o 

= - 2 ( l Q + i 2 + i h + i 6 + i 8 ) (33) 

where the I*s correspond to the five terms in A* (k) . By 
Erdelyi, et al. (195*0, we obtain, for n = 0,1,2,3,U: 

ha = e I e " PX ^n 1 F 1 ( " I " n > 2> ^ ( 3h) 

where 



^n = b 2n (Up)n+ (n + 1)1 (35) 



or, written out completely: 



-10- 




Fig. 1. Initial wave height T] versus a ; a = .5 , e = .001. 



-11- 




Fig. 1. (con't) 



-12- 



v = 



e\e- pX ~[b o (U P ) 2 1 '. lFl (-| , | , p\ 2 ) 



+ b 2 (Up) 3 2 I X F (- | , | , p\ 2 ) 



+ \(4 P ) U 3 ! ^ (-| , | , PX 2 ) 



+ b 6 (iip) 5 i+ • lFl (-| , | , pX 2 ) 

+ b 8 (Up) 6 5 I ^(-f , | , p\ 2 )] , (36) 

and this gives v as a function X for the shoreline a = . A 
similar treatment of (19) yields T| : 

00 
2 

11 = - \ + ^ | dk k 2 A(k) cos kX 
o 

00 

= - ~ + f dk k A (k) cos k\ 
o 

= - \ + \ ee " p ^[b o (Up) 1 lFl (- \ , \ , P x 2 ) 



+ b 2 (i+ P ) 2 1 • ^C- 1 , I , P x 2 ) 



+ b u (U P ) 3 2 i lFl (- 1 , § , pX 2 ) 



+ b 6 (Up) U 3 ! -^(-f , \ , PX 2 ) 



+ b 8 (l +P ) 5 1» • lFl (-| , § , pX 2 )] , 



(37) 



-13- 



and this gives T) as a function of X for the shoreline a = . 
Some typical plots of T\ and v against X are shown in Fig. 2. 
By (20) we can find the time corresponding to each value of X . 
Such a table of values is the implicit representation of T|(t) and 
v(t) . The same cases as shown in Fig. 2. are shown in Fig. 3«» 
plotting T| and v against t . It is easily seen by (20) that time 
can run "backwards" if v(X) increases faster than X/2 at any point 
X . Such a case would correspond to the wave breaking, and the 
solution must be discarded. However, an inflection point in the function 
t(X) is a useful criterion for determining values of e , a , and p 
such that the wave will almost, but not quite, break. 

We now turn to the aspect of amplification. The initial heights 
of the waves are known from the boundary conditions. The maximum run-up 
heights of the respective humps can be read off from Figs. 2. and 3« 
Their ratios determine the amplification factor of each of the two humps. 
By numerical investigation it was found that the amplification is essen- 
tially independent of a and p for a constant product ap . As long 
as e is small enough so that the wave does not break, the amplification 
is strictly independent of e , since T|(a,0) is proportional to e 
and Tl (0,X) is proportional to e (the v /2 term is zero at Tl ) . 

For values of T)(0,X) other than extremum values, T| is practically 

2 2\ 

proportional to e , as v /2 is 0(e). The ratio of the initial 

heights is similar to the amplification, in that this ratio is 

essentially independent of a and p for a constant ap . However, 

both the amplifications and the initial height ratios do vary with ap , 

as shown in Fig. U. 



-14- 




Fig. 2. Shoreline behavior (a = 0) of wave height Tl (solid line) 

and velocity v (dotted line) versus X. ; a = .5 , c = .001. 



-15- 




Fig. 2. (con't) 



-16- 




Fig. 3. Shoreline behavior (a = 0) of wave height T\ (solid line) 

and velocity v (dotted line) versus t ; a = .5 , e = .001. 



-17- 




Fig. 3. (con't) 



-18- 



10 



1.5 



2j0- 



OjO 



fication of Maward hump 



smptificotiofi of thot% hump 




-I I— I !_ 



1.0 



0.5. 



00 







25 



Fig. h. Amplification factors of the two humps, and the ratio of 
initial heights of the two humps (expressed as a number 
between and l) versus the product ap . 



We conclude that the amplification of the first hump (shoreward) 
is essentially constant, but that the amplification of the second 
hump (seaward) is strongly dependent on the height of the first hump. 
The maximum amplification occurs when the seaward hump is 0.625 the 
height of the shoreward hump. For ap between about 1.32 and 1.4l, 
the second hump washes up higher even though it was smaller to begin 
with. From (20) we see that the maximum value of e without breaking 

can be determined by making t(\) have an inflection point at the 

dv 

(This can be found from Fig. 2.) This maximum 



maximum value of 



o\ 



e is shown in Fig. 5. plotted against ap . For values ap and e 
below the curve, the wave does not break, and for values above the 



curve , the wave breaks , 



-19- 



03 



02 



e 
E 

Vf 



0.1 



00 



00 



Wove breaks in thit region. 
Solutions arc invalid. 



Wave does not break in 
this region. 



■ ' 



1.0 



15 



2.0 



Fig. 5. The maximum value of e for which the wave will not 
break versus the product ap . 



k. PROPAGATION OF THE WAVE 

Our discussion of the wave behavior in the (o",\) plane has been 
confined to determining the (0,X) behavior given the (a,0) shape. 
This solves the problem for a particular shape with zero initial velocity. 
The amplification figures may be questioned, as the stationary initial 
shape might be represented as a superposition of two traveling waves, 
each with half height. For that part rf the wave which is incident on 
the beach this might imply amplification factors of twice the previously 
quoted values. In order to investigate these questions, one must solve 



-20- 



for the general (a,X) behavior, particularly for large values of 

X . Unfortunately, for our expression A(k) , the integral (25) 

and (18, 19) with the integral form of $ have no closed-form solution 

for arbitrary (o,X) , and must be solved numerically. Further, the 

o 

approximate expression for T](a,X) is (neglecting the v /2 term which 

is 0(e 2 )): 

00 

fl(a,X) = 5 J <*k k 2 A ( k ) J ( to ) cos *& 
o 

00 
= e J dk P(k)e" k / kp J Q (ka) cos kX (38) 



o 



where 



P(k) = k(b + b g k 2 + b^k + b,k + b Q k ) 



For large values of X , the integrand oscillates rapidly, making 
numerical integration difficult. The method of stationary phase or 
steepest descents for approximating this integral is impractical 
since we suspect the integral to be largest when a is also large; 
the wave being propagated in time (represented by X) travels out to 
sea (represented by increasing the values of a). For large a and X 
the integral oscillates rapidly with two frequencies, thus malting these 
methods inapplicable and numerical integration even more difficult. 

That the wave is propagated out to sea can be demonstrated 
mathematically in two ways. By Whittaker and Watson (1962), we can 
represent J as 



-21- 

00 

J (ka) ■ - | dt sin(ka cosh t) . (39) 

O TT J 
C 

Putting this in (38) and reversing the order of integration we have 

00 00 

2 

T)(a,\) = e - f dt [ dk P(k)e~ k ' p sin(ka cosh t) cos kX . (Uo) 

O O 

Setting t = a cosh t , we can rewrite (Uo) as 

00 00 

2 

Tl(a,X) = e |J dt J dk P(k)e" k / Up •§ [sin k(x+X) + sin k (t-X) ] . (Ul) 

o o 

The k integral, as we have seen previously, is a sum of confluent 

2 
hypergeometric functions which will decay like exp(-p(T+X) ) and 

2 
exp(-p(T-X) ) . For large values of X , only the terms with 

2 
exp(-p(T-X) ) behavior will contribute significantly to the t integral, 

and then only when (t-X) is small. Now (t-X) is small only when 

a cosh t is near X . This tells us three things. First, for a 

much larger than X , (a cosh(t) - X) ^ (a-X) is large and the integral 

is small. For a near X , (t-X) is small for small t and the 

integral has a significant non-zero value. For a small, (t-X) is 

small only when t is large, but since t ~ ae /2 , not too much time 

is spent by the t integral in this region where (t-X) is small. The 

integral then has a significant non-zero value, but is much smaller 

than for a near X . These qualitative arguments are intended to 

demonstrate that for increasing values of time and therefore of X , 

the large values of T] occur for increasing a and therefore for 

increasing distance seaward. 



-22- 



The second method of demonstrating propagation is the one that is 
feasible for computerized numerical integration. One writes J as 



J (to) = J (kcr ) - / -|- cos(ka - ? ) + J~T~ cos (ka - ?) (U2) 

o x o v V TTka k ' Vnka h' v ' 



and the integral (38) for Tj is written as 



7l(a ,X) = e j dk P(k)e _k / Up [j Q (ka) - J J~ a cos(ka - £) ]cos kX 



- e 



L T 1 + I 2J 



+ e J dk P(k)e" k ' P J-fj cos(ka - J) cos kX 

(U3) 



Now I. has had the oscillating character of J (ka ) taken out ror 
1 o ' 

large values of a , and the result is an integral of a relatively 
smoothly varying function times the rapidly oscillating cos kA . We 
can integrate this numerically choosing the Ak such that nAkX = 2rc 
where n is some integer. We expect this integral to be small. I„ 
on the other hand can be integrated analytically by writing 

cos(ka - J ) cos k\ = |Jcos(k(a + X) - \) + cos(k(a - X) - J ) j 



-i- I cos k(a + X) + sin k(cr + X) 
2/2 L 

+ cos k(a - X) + sin k(a - X) ] . W 



-23- 



We obtain (again) a stun of .F_ functions that behave like 



2 



2 



e' pT ± P (a,P,prJ) (U5) 



where 



t + = a ± X (U6) 

and a and (3 are characteristic of the specific term involved. Once 
again we note that the t terms are small and that the most significant 
contributions to H come from the t terms when a is near X 
(meaning the wave is being propagated out to sea). The result of such 

numerical and analytic integration of (38) is shown in Fig. 6. for a 

p 
specific case. Here the v /2 term is not ignored, the same arguments 

as above being used to compute v(a,X). 

We note that v(a,X) is strictly anti- symmetric in X and that 
therefore T|(a,X) is symmetric. By (20),t(a,X) is strictly anti- 
symmetric in X . Fig. 6. can therefore be used running time backwards 
by replacing X by -X to obtain prior times, noting that Tl(a,X) 
remains the same and v is replaced by -v , as one would expect. 

We conclude this section with a remark on amplification. By the 
series shown in Fig. 6. we can see the results of the superposition of 
an incoming and outgoing wave, especially as it applies to the seaward 
hump. Since the effects of amplification have already begun by the 
time the two parts separate, it is difficult to assess what the separate 
"heights" of the incoming and outgoing waves are in relation to the 



-24- 




Fig. 6. The wave height T) versus x for the wave shape given by 
a = .5 , ap = 1.25 , e = .001. Note that t = X/2 + 0(e) , 
so that the above graphs for \ = 0., .2, ... , 3.0 are 
approximately also for t = 0., .1 , ... , 1.5 • 



-25- 



X«1.6 



X-1.8 



X»2.0 



X«2.2 





X»2.4 



X'2.6 





2 

:2 
2 

-2 
.2 

2 >< 

2 5 


t2 
.2 

-.2 
2 

2 
2 

■2 
2 

2 



Fig. 6. (con't) 



-26- 



total height of the wave at t = . The number l/2 seems plausible 
enough by an inspection of Fig. 6., so we conclude that the amplifica- 
tions recorded in Fig. h. should perhaps really be double their value. 

5 . A NUMERICAL EXAMPLE 

Suppose for example that one wished to consider two mounds of 
water with equal heights of 5 feet. Further suppose that their separation 
distance (crest to crest) is 10 feet, and that the bottom has slope a . 
Unfortunately, in this formulation, we are not permitted to specify the 
shore-to-trough distance independently of the crest-to-crest spacing 
and the height ratio. For our shape here, the shore -to- trough distance 

o 

equals .5*+ the crest-to-crest spacing or 5.*+ x 10 feet. From Fig. h. 
we see that ap = 1.33 and that the amplification of the first and 
second crests will be, respectively, 1.7 and 2.3. If the wave does 
not break, T\* has the same amplification characteristics as Tl since 
T\* = at& Tl . If the wave is well behaved, then, we will have T|* 
ultimately reaching 8.5 feet and 11.5 feet run-up for the first and 
second humps, respectively. For a = .1 , maximum inundations are 
85 feet and 115 feet. For ap = 1.3 and the admittedly arbitrary 
choice of a = .5 , the initial l\/e is about 2.1 x 10 and their 
x separation is about .116. Then from the definitions of the dimension- 
less variables, 



k 

SL = 8.6 x 10 ft. 
o 



-27- 



and 



e = 2.76 x 10" 3 /a 



From Fig. 5. the maximum value of e for our case is .13, so for 
slopes greater than ,021 the wave will not break. 

6. ACKNOWLEDGEMENTS 

The author wishes to thank Harold G. Loomis, Gay lord R. Miller, 
and Jimmy C. Larsen for their kind encouragement and helpful advice 
in this work. The numerical computations were carried out at the 
Statistical and Computing Center at the University of Hawaii. 



-28- 



7 • REFERENCES 



1. Carrier, G. F., and H. P. Greenspan (1958), 'Water waves of 
finite amplitude on a sloping beach," J. Fluid Mech. k, 97- 

2. Carrier, G. F. (1966), "Gravity waves on water of variable 
depth," J. Fluid Mech. 2h, 6hl. 

3. Stoker, J. J. (1948), "The formation of breakers and bores," 
Commun. Pure Appl . Math. 1, 1. 

h. Erdelyi, A., W. Magnus, F. Oberhettinger , F. G. Tricomi, Eds. 

(195*0, 'Tables of integral transforms,'' Bateman Manuscript 

Project, California Institute of Technology, 1j (McGraw-Hill 

Book Company, Inc., New York). 
5. Whittaker, E. T. , and G. N. Watson (1962), "A course of modern 

analysis ," (Cambridge University Press, London). 



29 



ON THE CROSS-STREAM VARIATION OF THE fc-FACTOR 

FOR GEOMAGNETIC ELECTROKINETOGRAPH DATA 

FROM THE FLORIDA CURRENT OFF MIAMI 

Frank Chew x 

The Bissett-Berman Corporation, Santa Monica, California 

ABSTRACT 

A factor, k, is used to convert Geomagnetic Electrokinetograph (GEK) observations of 
ocean currents to the current speeds. It is usually approximated in terms of the kinematic 
structure of a current and is generally assumed to be constant across the width of a stream. 
Recent direct transport and surface current measurements across the Florida Current off 
Miami were compared with GEK profiles. There was a cross-stream change in the fc-factor 
that, in location and magnitude, could account for double speed maxima often observed 
in GEK profiles across this stream. 



INTRODUCTION 

The measurement of ocean currents by 
the Geomagnetic Electrokinetograph (GEK) 
is subject to many possible errors ( Longuet- 
Higgins, Stern, and Stommel 1954). To 
correct for these errors, von Arx ( 1950 ) 
suggested the use of an empirical Zc-factor, 
a ratio of the magnitude of the GEK output 
to the actual current speed. For most cur- 
rents, the major error is usually thought to 
stem from the effect of the depth of the 
current: The error increases as the current 
depth increases relative to the depth of the 
total water column. In terms of the fc-factor, 
this is equivalent to its approximation when 
one considers only the subsurface kinematic 
structure relative to the surface current. 
The fc-factor varies from region to region, 
but for a given section of a stream it has 
been generally assumed to be constant (see 
Webster 1965). Because of practical diffi- 
culties, it has not been possible to test either 
the adequacy of the approximation or the 
validity of the assumption. The purpose 
here is to discuss a test of both in a related 
but restricted context. 

Many investigators have constructed 
cross-stream profiles of the Florida Current 
off Miami from uncorrected GEK observa- 
tions. These profiles of the downstream 
surface flow often show a double speed 






1 Present address : Physical Oceanography Lab- 
oratory, Institute for Oceanography, Environmental 
Science Services Administration, Silver Spring, 
Maryland. 



maximum. An example of this feature is 
shown in Fig. 1, along with samples from 
the current in the Yucatan Channel and off 
Onslow Bay as illustrations of its rather 
widespread occurrence. When underway, 
the GEK records the signal from the sea 
continuously. However, the magnitude of 
the signal takes its numerical origin from a 
zero point determined, in practice, only at 
discrete intervals. Because of the uncer- 
tainty of the zero points between such de- 
terminations or "fixes," the record of the 
signal between fixes is usually not consid- 
ered in profile construction. Further, the 
spacing of the GEK fixes is often of the 
order of the distance between the maxima. 
Hence, good resolution of the feature can- 
not be expected in all profiles. Similarly, 
mean profiles constructed from GEK fixes 
averaged over distances comparable to the 
distance between the double speed maxi- 
ma will tend to suppress it. This can be 
demonstrated by using a method suggested 
by Dr. A. Court and applied by Chew 
(1965). Of the 623 GEK observations con- 
sidered, the three most easterly observations 
were discarded. The remaining 620 were 
then divided into 20 groups of 31 each. The 
pertinent GEK data and computation are 
tabulated (Table 1) and feature a pro- 
nounced midstream speed minimum in the 
uncorrected GEK profile at zone 8. Elemen- 
tary statistical tests of the difference be- 
tween the means for zones 7 and 8 indicate 
the difference is highly significant. This un- 



73 



74 



FRANK CHEW 



YUCATAN 



MIAMI 



ONSLOW BAY 



200 



160 



120 



Cm/sec 




Fig. 1. Uncorrected, GEK cross-stream profiles of the surface current at three areas (the respective 
sources are Texas A&M University, University of M iami, and Woods Hole Oceanographic Institution ) . 



corrected GEK feature is suppressed if the 
same data are grouped into 10 zones of 62 
observations each. This appears to be the 
case for the mean profile reported by Web- 
ster (1965) for the Florida Current off 
Miami. It seems, therefore, that the feature 
is fairly persistent and is used as a conve- 
nient focus to conduct a limited testing of 
the adequacy of the approximation that the 
fc-factor is primarily a function of the surface 
current relative to the subsurface kinematic 
structure. The validity of the assumption 
that the fc-factor has no significant cross- 
stream variation is also tested by asking 
whether the cross-stream variation in the 
approximate A>factor can account for the 
biaxial feature in the downstream compo- 
nent. The basic data for the test are those 
reported by Richardson and Schmitz (1965), 
who also generously supplied additional 
unpublished observations. I am indebted 
to Dr. J. A. Knauss for valuable suggestions 
and to Dr. F. F. Koczy for his encourage- 
ment. 



THE fc-FACTOR 

An approximation 

In the absence of geomagnetic storms and 
away from the edges of a current, Long- 
uet-Higgins et al. (1954) show that errors 
in GEK readings are due principally to 
vertical variations of velocity, horizontal 
velocity shear, and conductivity of the 
underlying sea bed. The electrical effect of 
horizontal shear is proportional to the com- 
ponent of the earth's magnetic field trans- 
verse to the direction of the component of 
velocity of interest. In the Florida Current 
off Miami, this is the east-west component 
which, at this location, is fortuitously small 
relative to the vertical earth component. 
Thus, error from this source can be ne- 
glected. The effect of sea bed conductivity 
depends on the ratio of conductivity of 
seawater to that of the sea bed. The effec- 
tive conductivity of the sea bed underlying 
the Florida Current has not been deter- 
mined; it will be assumed that it is of the 



CROSS-STREAM VARIATION OF THE fc-F ACTOR 



75 



same order of magnitude as that of the 
English Channel; this gives a ratio of the 
order of 10 3 . For this ratio, the sea bed 
conductivity is a critical factor if the width 
of the current is 10 3 times its total depth 
(see Longuet-Higgins et al. 1954). In the 
Florida Current, the corresponding dimen- 
sion ratio is an order less, and hence the 
sea bed conductivity does not appear to be 
critical. If this error is considered to be 
negligible relative to that due to the vertical 
kinematic structure, then for a given cur- 
rent component, V, we have the approxi- 
mation 



Table 1. GEK data, grouped in 20 zones, with 
equal number of observations in each zone (\c = 1) 



k = V s /(V s -V) 



(1) 



where V (when the electrical conductivity 
of the water is uniform ) is the mean speed 
taken throughout the total water column; 
V s ( the speed at the surface ) is the quantity 
the GEK is intended to measure; and 
(V g -V) is what the GEK does measure, 
given the approximation. The GEK deter- 
mines the velocity vector of the surface 
current by measuring its components. Thus, 
the fc-factor for each component is generally 
different; an exception occurs only when 
the velocity remains constant in direction 
with depth. In applying equation ( 1 ) , care 
must be taken to avoid situations where the 
magnitude of V approaches that of V s . 
Since k can then no longer be reliably de- 
termined, the effect of small errors in V 
and V s is greatly magnified. More impor- 
tantly, the GEK in this situation would not 
measure the electrical effect of ( V 8 - V ) 
but instead, those effects that are neglected 
in arriving at the approximation. Also, sit- 
uations where V is greater than V s must be 
avoided, because equation ( 1 ) is then no 
longer applicable; an example is seen in 
the next section. 

An evaluation 

Richardson and Schmitz ( 1965 ) have 
made direct current measurements of the 
Florida Current off Miami; for the north- 
ward component, their measurements are 
accurate to within 1-2% of the absolute 
magnitude. The use of their data to eval- 
uate equation ( 1 ) gives the numbers tabu- 



Zone 


Longitudinal 
interval 


Mean 
north 
velocity 
compo- 
nent 


(cm/ 
sec) 


n 








(cm/ sec) 






1 


80°05.4'-80 


°04.3' 


42.5 


6.8 


31 


2 


04.3'- 


03.0' 


69.0 


8.6 


31 


3 


03.0'- 


00.8' 


62.0 


9.3 


31 


4 


00.6'-79°58.8' 


82.7 


6.3 


31 


5 


79°58.8'- 


56.4' 


90.2 


8.0 


31 


6 


56.3'- 


54.5' 


105.1 


6.5 


31 


7 


54.5'- 


52.5' 


106.1 


4.9 


31 


8 


52.5'- 


52.4' 


85.2 


3.9 


31 


9 


52.4'- 


49.3' 


117.0 


5.5 


31 


10 


49.2'- 


47.1' 


117.2 


5.5 


31 


11 


47.1'- 


45.9' 


103.4 


3.3 


31 


12 


45.9'- 


44.0' 


106.3 


4.3 


31 


13 


44.0'- 


41.0' 


98.8 


5.9 


31 


14 


41.0'- 


38.0' 


84.1 


4.4 


31 


15 


38.0'- 


35.1' 


63.8 


7.4 


31 


16 


35.0'- 


32.0' 


63.7 


5.3 


31 


17 


31.1'- 


28.0' 


49.8 


5.1 


31 


18 


28.0'- 


25.5' 


37.8 


5.0 


31 


19 


25.4'- 


22.0' 


31.4 


5.6 


31 


20 


21.8'- 


19.5' 


23.1 


5.4 


31 



lated in column 7, Table 2, where identify- 
ing information is also included. At all 
locations V s is greater than V, except at 
location 83.32 km on 16 August 1964. The 
factor k, as given by equation (1), is not 
computed for this case. On this occasion, 
a GEK measurement would indicate a 
countercurrent; it is possible that past GEK 
indications of countercurrents off Miami 
were due to this cause and are spurious. 
Omitting this case, the computed k values 
range from 1.2 to 3.0 and average 1.9. Their 
cross-stream distribution is plotted in Fig. 2. 
It is apparent from Fig. 2 that k varies 
across the stream, but its statistical signifi- 
cance has not been determined, partly be- 
cause the data are too few for a meaningful 
test, and partly because of the neglect of 
temperature and salinity effects in evalu- 
ating V. Consideration of a least-squares 
fitting to the plotted data leads to at least 
two possibilities. One is a single line slop- 
ing up eastward and spanning the entire 
range corresponding to the width of the 
current. Another is the two more or less 
parallel lines that have been fitted as shown, 
with the implication that they are joined 



76 



FRANK CHEW 



Table 2. A computation for k 



Date 



Distance east 
of Virginia 
Key (km) 



Depth 

of sea 

bed (m) 



North— south 
component 
of transport 

(m 2 /sec) 



Surface cur- 
rent north 
component 

(cm/sec) 



Mean current 

through total 

depth, north 

component 

( cm/sec ) 



k* 



Afcf 



16 Aug 1964 


8.55 


54 


1 


13 


2 


1.2 


0.03 




16.35 


289 


157 


215 


54 


1.3 


0.04 




26.28 


349 


352 


253 


101 


1.7 


0.11 




35.47 


688 


533 


250 


78 


1.5 


0.07 




44.26 


774 


701 


218 


91 


1.7 


0.12 




53.55 


807 


735 


177 


91 


2.1 


0.22 




62.90 


839 


615 


119 


73 


2.6 


0.41 




72.51 


763 


397 


80 


52 


2.9 


0.54 




83.32 


382 


269 


31 


70 






17 Aug 1964 


10.39 


141 


90 


189 


64 


1.5 


0.08 




12.25 


241 


124 


186 


52 


1.4 


0.05 




14.31 


270 


146 


200 


54 


1.4 


0.05 




21.28 


356 


282 


209 


79 


1.6 


0.10 




30.83 


375 


434 


233 


116 


2.0 


0.20 




39.69 


838 


639 


215 


76 


1.5 


0.08 




48.71 


775 


705 


174 


91 


2.1 


0.23 




57.65 


800 


700 


132 


88 


3.0 


0.60 




67.09 


824 


607 


120 


74 


2.6 


0.42 


19 May 1965 


32.4* 


350 


340 


183 


97 


2.1 


0.24 


15 Mar 1965 


38.6* 


860 


410 


140 


48 


1.5 


0.08 


6 Apr 1965 


64.4* 


830 


633 


134 


76 


2.3 


0.30 



* From equation ( 1 ) . 
t From equation ( 4 ) . 
% Unpublished data supplied by Dr. E. W. Richardson. 



by a third with a reverse slope in the cross- 
stream interval between 32.5 and 36.0 km. 
This fitting has three noteworthy features. 
First, the overall scatter is smaller than a 
single line fit. Second, between 32.5 and 
36.0 km (the vicinity where the sea bed 
drops from 400- to 800-m depth ) , the trend 
of k reverses, losing in magnitude rather 
abruptly almost all it gained in the preced- 
ing interval. And, third, although the two 
separate rising trends are unmistakable, the 
scatter is least in the vicinity of the ob- 
served current axis, possibly implying a 
more variable kinematic structure on both 
flanks of the axis. This second possibility 
constitutes the hypothesis in the test con- 
sidered in the section following. 

In evaluating equation (1), we have 
assumed a constant electrical resistivity for 
the water. Had corresponding temperature 
and salinity information been available, we 
should have evaluated V according to the 
equation 



where r is the electrical resistivity of the 
water and the integration of depth extends 
from the sea surface, 0, to the sea bed, h. 
Neglecting the small pressure effect, the 
resistivity is least where temperature and 
salinity are highest; for the Florida Current 
low resistivity corresponds approximately 
to the layers where V is large. Thus, the 
magnitude of V in column 6, Table 2, is 
an underestimate in all cases where V s is 
greater than V. To compensate, a positive 
quantity, AV, representing the underesti- 
mate, must be added to the computed V. 
For a given V s , the effect of AV on k is, 
from equation ( 1 ) , to the same approxima- 
tion 

fc(AV) 



Ak 



(3) 



— dz, 
o r 



(2; 



(V s -V) 

From temperature and salinity sections, A V 

is estimated to be Via of V. Using this, 

equation (3) is found from 

kV 

Afc = =-, (4) 

10(V S -V) 



CROSS-STREAM VARIATION OF THE k-F ACTOR 



77 



a 16/8/64 
x 17/8/64 

\\ 19/5/64 
• < 2 15/3/65 

1 3 6/4/65 



-a — FLORIDA CURRENT 
OFF MIAMI 16/8/64 
FROM RICHARDSON 

GEK PROFILE FOR 

k FACTOR ON LEFT 



200 



160 




Cm/s 



120 



Fig. 2. Left, a plot of computed values of k across the Florida Current off Miami. Right, observed 
(solid) and its implied, uncorrected GEK (dashed ) profiles of the current off Miami. 



column 8, Table 2; in all cases Afc amounts, 
at most, to 207" of k. However, with Afc 
proportional to k and to be added to the 
latter, this correction will accentuate the 
slope of the least-squares lines. Thus, the 
k pattern suggested in Fig. 2 is conserva- 
tive, actually minimizing the cross-stream 
gradient of k, especially in the interval be- 
tween 32.5 and 36.0 km. 

A test 

When the profile of V s corresponding to 
a pattern of k is known, the two together 
imply a specific uncorrected GEK profile, 
obtainable by simply dividing k into V s at 
corresponding points in accordance with 
equation (1). For the data from which k 
has been computed, Richardson and Schmitz 
( 1965 ) give two profiles of V s obtained on 
successive days. The two differ in some 
respects and averaging them modifies the 
profile of 16 August 1964, broadening 
slightly the current axis and changing 



slightly the lateral shear, but otherwise 
leaving the overall pattern unchanged. For 
simplicity, only the profile for 16 August 
has been used and is reproduced as the 
top curve on the right side of Fig. 2. Use 
of the 17 August profile or one obtained 
by averaging the two gives substantially 
the same result, as the critical feature of 
a broad, relatively flat current axis remains. 
The corresponding, implied, uncorrected 
GEK profile for 16 August is shown by the 
broken curve ( Fig. 2 ) . Given the relatively 
flat and broad current axis of the solid 
curve, the midstream minimum in the 
broken curve results largely from the high 
fc-value there; similarly, the primary maxi- 
mum in the broken curve results from a 
low fc-value, and so on. 

DISCUSSION AND CONCLUSION 

The implied, uncorrected GEK profile 
preserves the extent and the shape of the 
original anticyclonic shear reasonably well; 



78 



FRANK CHEW 



although the original cyclonic shear is less 
well preserved, it is still not unreasonable. 
On the other hand, where originally there 
is a single current axis some 10 to 15 km 
wide, there are now two narrow axes sep- 
arated by an unmistakable minimum in the 
implied profile. In general shape and in 
location and magnitude of the double 
maxima, the implied profile bears consider- 
able resemblance to the observed GEK pro- 
files. 

The value of k computed according to 
equation ( 1 ) and averaged across j.he 
stream may be compared to the correspond- 
ing observed fc-value reported by Wagner 
( 1955 ) . For each complete crossing of the 
current, he compared the total drift indi- 
cated by the GEK to the corresponding 
drift given by navigation to obtain an 
average value of k. For 14 such crossings 
completed in 1952-1953, he obtained a 
mean of 1.7 and a range of 1.2 to 2.2. This 
compares favorably with the 1.9 for con- 
stant electrical resistivity and 2.1 for vari- 
able resistivity found in this study. 

For the Florida Current off Miami, the 



approximate equation ( 1 ) appears ade- 
quate, and the feature of double speed 
maxima is probably spurious. 

REFERENCES 

Chew, F. 1965. On correcting geomagnetic elec- 
trokinetograph data from the Florida Current. 
Lockheed Report 19194, Burbank, California. 
( Unpublished manuscript. ) 16 p. 

LoNGUET-HlGGINS, M. S., M. I. STERN, AND H. 

Stommel. 1954. The electrical field in- 
duced by ocean currents and waves, with ap- 
plications to the method of towed electrodes. 
Papers Phys. Oceanog. Meteorol., 13: 1-37. 

Richardson, W. S., and W. J. Schmitz. 1965. 
A technique for the direct measurement of 
transport with application to the Straits of 
Florida. ]. Marine Res., 23: 172-185. 

von Arx, W. S. 1950. An electromagnetic 
method for measuring the velocities of ocean 
currents from a ship underway. Papers Phys. 
Oceanog. Meteorol., 11: 1-62. 

Wagner, L. P. 1955. Graphic representations 
and comments on transects across the Florida 
Current, p. 24-53. In Some results of the 
Florida Current study. Tech. Rept. ML 6787, 
54-7. University of Miami, Miami, Florida. 

Webster, F. 1965. Measurements of eddy fluxes 
of momentum in the surface layer of the Gulf 
Stream. Tellus, 17: 239-245. 



Reprinted from: THE INTERNATIONAL JOURNAL 
OF OCEANOGRAPHY AND LIMNOLOGY Vol. 1, No. 2 

New Method for Boron Determination in Sea Water 
and Some Preliminary Results 



30 



ABSTRACT 



INTRODUCTION 



John D. Gassaway 

Environmental Science Services Administration, Institute for Oceanography, 
Silver Spring, Maryland 20910 

The 1 ,1 ' -dianthrimide method for the determination of total boron in 
sea water is described. With the outlined procedure and apparatus, a 
standard deviation of approximately ± 0.30 mg per liter, or less, is ob- 
tainable. Standard sea water P s , ( was found to have a boron content of 
5A9 ± 0.17 mg per liter and a boron-chlorinity ratio of 0.0259 ± 0.0005. 
No single, definite relation was observed between oxygen, salinity, and 
total boron at station BB 355-033, and lack of data prevent any conclu- 
sions concerning the identification of water masses with total boron. 

The mannitol method tor determining borate-boron in sea water is based 
on the work of Thompson (1893). Various investigators, i.e., Igelsrud, 
Thompson, and Zwicker (1938), Gast and Thompson (1958), and 
Noakes and Hood (1961) have modified this method for determining 
boron in sea water. The method is pH sensitive and directly measures 
the borate concentration and not the boron concentration. Also, the end 
point is difficult to judge with accuracy. 

Parker and Barnes (1960) described a fluorimetric method for the de- 
termination of boron in sea water and obtained a precision of ± 0.1 ppm 
for a single determination. This method requires the construction of a 
fiuorimeter, the de-oxygenation of the alkaline borate and the ethanolic 
benzoin solutions, and the removal of cations with an ion exchange resin 
before the determination. 

Kawaguchi (1955) used carmen red for the photometric determination 
of boron in sea water, but first had to separate boron as methyl borate. 
Reynolds and Wilson (1961) employed a spectrochemical method in- 
volving spark excitation for determining boron in saline waters. 

Greenhalgh and Riley (1962) investigated a curcumin method for the 
determination of boron in sea water. This is a simple procedure and does 
not require separation of boron from sea water. Humidity affects the pre- 
cision of this method; therefore, it must be carried out in a completely 
homogenous liquid organic atmosphere. The salts in sea water reduce the 
sensitivity of the method and correction factors for the evaluation of bor- 

Int. J. Oceanol. & Limnol. Vol. 1, No. 2. p. 85-90. 



BORON DETERMINATION IN SEA WATER 



85 



on are necessary. The correction factor for sea water with a chlorinity of 

20o/ 00 is8.9o/ . 

A number of factors, including sensitivity, ease of use, interferences 
from other elements, and knowledge of optimum conditions for color de- 
velopment determines the choice of a particular reagent for the spectro- 
photometric determination of an element. Ellis, Zook, and Baudisch 
(1949) investigated a number of organic compounds for their suitability 
as colorimetric reagents for boron and found l,l'-dianthrimide to be the 
best colorimetric reagent. 
PROCEDURE Four hundred milligrams of l,l'-dianthrimide are dissolved in 100 ml of 
concentrated sulfuric acid. This reagent is diluted to a 1:20 concentration 
with concentrated sulfuric acid (v/v) immediately before the l,l'-dian- 
thrimide is added to the sample. For satisfactory results a freshly diluted 
solution must be prepared daily. 

A 50-ml aliquot of sea water is diluted to 250 ml with distilled water 
(v/v) and 2- to 4-ml aliquot of this solution is placed in a teflon beaker to 
which one milliliter of 0.1 N calcium hydroxide is added. The sample is 
placed in the oven, evaporated to dryness at 100C, and cooled to room 
temperature. Ten milliliters of l,l'-dianthrimide solution are added, and 
the beaker containing the sample is placed in an oven for 90 min at 100 C. 
It is then cooled in a desiccator to room temperature, and the absorbance 
is read in a spectrophotometer at 625 nnx The color of the reagent ranges 
from green to blue. 
Discussion Dilutions of 1:5, 1:10, and 1:20 may be used, with the slope of the stand- 
ard curve approximately the same for all dilutions. The absorption co- 
efficient of 1:20 is less than a 1:5 or 1:10 dilution, allowing more concen- 
trated solutions to be analyzed. 

As there are no energy limitations at 625 m/i, the choice of the sample 
volume used depends on the instrument. The limiting factors vary from 
one instrument to another, and it is necessary for the analyst to determine 
the best values for his own particular spectrophotometer. It has been 
found that samples with an absorbance of 0.215 to 0.500 exhibit minimum 
variance. 

The sample may be incubated at 90C for 3 hr, 100C for 1-1/2 hr, or 1 hr 
at HOC in boron-free glass or plastic containers. At 90C, the time for anal- 
ysis is increased with no increase in accuracy, while at HOC the temper- 
ature of the oven must be carefully regulated, because temperatures ex- 
ceeding 1 10C may cause the reagent to break down rapidly, giving a red- 
dish-brown color. 

The samples are cooled in a desiccator as traces of moisture may inter- 
fere with the reagent. A one-centimeter silica cell is used for the absorb- 
ance measurement. 

High concentrations of oxidizing or reducing material and dissolved 
organic matter give anomalous results. If the technique as outlined above 



OCEANOLOGY AND LIMNOLOGY 



86 



TABLE 1. The boron content and chlorinity ratio for standard sea water P 34 . 



Chlorinity 



19.360 



Number of 
samples 



Boron 
content 



5.49 -+■ 0.17 



B/Cl 



0.0259 ± 0.0005 



DISSOLVED OXYGEN 

(ml/1) 

0.00 2.00 4.00 6.00 

~i — i — i — i — i — r 



TOTAL BORON B/Cl 

(mg/l) (xlO" 2 ) 

4.20 4.60 5.00 2.00 2.20 2.40 2.60 




FIGURE 1. The variation of the boron content, B/Cl, and oxygen with depth at sta- 
tion BB 355-033. The horizontal lines represent the standard deviation 
of the B content and the B/Cl ratio. 



BORON DETERMINATION IN SEA WATER 



87 



SOME PRELIMINARY 
RESULTS 



Discussion 



is followed, the concentration of the interfering ions and organic com- 
pounds is too small to affect the results. Buffering solutions and solutions 
with a high salt content do not affect the results significantly (Powell and 
Poindexter, 1957). 

This method yields total boron. The temperature at which the sample 
is heated and the sulphuric acid decompose the organic compounds which 
form complexes with boron (D. G. White, personal communication). 
Also, the complex boron concentration reported by other workers (Noakes 
and Hood, 1961) is usually less than the standard deviation of the method. 

Using the outlined procedure and apparatus, the standard deviation 
obtainable is approximately ± 0.30 mg per liter, or less. 
The results of the analysis of standard sea water P 34 , I.A.P.O. Standard 
Sea Water Service, Chalottenlund Slot, Denmark, are listed in Table 1 
and those from station BB 355-033 are shown in Fig. 1. The location of 
the station from where the samples were taken is 46° 23.9 N and 125° 
22.3 W, approximately 100 miles west of the mouth of the Columbia Riv- 
er. The sea water samples were collected with Nansen bottles which were 
drained immediately upon retrieval into polyethylene containers, frozen, 
and returned to the laboratory where they were thawed and analyzed. The 
boron content is measured in milligrams of boron per liter and the chlor- 
mity ratio (B/Cl) is milligram-atoms boron per chlorinity (X 10 2 ) (Igels- 
rud, Thompson, and Zwicker, 1938). Oxygen is reported in milliliters per 
liter, and the depth is in meters. 

Standard sea water P 34 has a boron content of 5.49 ± 0.17 mg per liter 
and a boron-chlorinity ratio of 0.0259 ± 0.0005. This sample was taken 
from one ampule. The boron chlorinity ratio is extremely high, and if 
the ampule is a boron containing glass, this high value might result from 
the solution of the glass by the contained water. 

In Table 2 the maximum and minimum concentration of the boron- 
chlorinity ratio in sea water, as reported by other authors, is tabulated. 
These results agree favorably with those reported in this paper. 

There is an over-all increase of total boron with depth and this rate of 
increase is greater than that of the chlorinity (Fig. 1). At this particular 
station, there is no linear relationship between the total boron and chlor- 
inity. Instead, the total boron content varies with depth as in Noakes and 
Hood's (1961) stations and in one Atlantic Ocean station examined by 
Glebovich (1946). 

At station BB 355-033, below 300 m, there is a direct relationship be- 
tween the total boron and oxygen (Fig. 1). This is the opposite of the 
findings of Igelsrud et al. (1938), but agrees with Glebovich (1946). The 
three stations examined by Noakes and Hood (1961), together, do not 
show any single, definite relationship. Miyake and Sakuri (1952) observed 
no relation between oxygen and boron with depth in the water column, 
but they demonstrated the possibility of correlating the boron content 



OCEANOLOGY AND LIMNOLOGY 



88 



with different water masses. There is, apparently, no single, definite re- 
lationship between the oxygen and the total boron content, and the lack 
of data prevents any comment on tracing water masses with boron. 
CONCLUSIONS A precise and accurate method for determining total boron in sea water 
was developed. This technique is sufficiently simple to be used for routine 
work and does not entail separation of the element. A standard deviation 
of ± 0.30 mg per liter is readily obtainable. 

Standard sea water P 34 has a boron content of 5.49 ± 0.17 mg per liter 
and a chlorinity ratio of 0.0259 ± 0.0005. 

From the one station examined in this paper and those cited in the 
text, there is, apparently, no single, definite relationship between total 
boron, oxygen, and salinity, or chlorinity. 



REFERENCES Ellis, G. H., E. G. Zook, and O. Baudisch. 1949. Colorimetric methods for the 

determination of boron. Anal. Chem., 21, 1345-3148. 
Gast, J. A., and T. G. Thompson. 1958. Determination of the alkalinity and borate 

concentration of sea water. Anal. Chem., 30, 1549-1551. 
Glebovich, T. A. 1946. Boron in the sea. Trudy Biogeokhim. Lab. Acad. Nauk. 

SSSR., 8, 227-252. 
Greenhalgh, R., and J. P. Riley. 1962. The development of a reproducible spectro- 

photometric curcumin method for determining boron, and its application to 

sea water. Analyst, 87, 970-976. 
Igelsrud, I., T. G. Thompson, and B. M. G. Zwicker. 1938. The Boron Content of 

Sea Water and of Marine Organisms. Amer. J. Sci., 35, 47-63. 



TABLE 2. The maximum and minimum concentration of the boron chlorinity ratio 
in sea water as reported by other authors and this paper. 



Maximum B/Cl Minimum BjCl 



Method 



Author 



0.0250 


0.0202 




Mannitol 


Igelsrud et al. (1938) 


0.0254 


0.0229 




Mannitol 


Glebovich (1946) 


0.0225 


0.0219 




Mannitol 


Gast and Thompson 

(1958) 


0.0232 


0.0221 




Fluorimetric 


Parker and Barnes 

(1960) 


0.0226 


0.0205 




Mannitol 


Noakes and Hood (1961) 




0.02112 


(analyzed 


Curcumin 


Greenhalgh and Riley 




one sample) 




(1962) 


0.0246 ± 0.0009 


0.0211 ±0.0008 


l.l'-dianthrimide 


(This paper-excluding 










standard sea water 










P 34> 



BORON DETERMINATION IN SEA WATER 



89 



Kawaguchi, H. 1955. Colorimetric determination of traces of boron. Japan 

Analyst, 4, 307-310. 
Miyake, Y. and S. Sakuri. 1952. Boron in sea water as an indicator for the water 

mass analysis. Sea and Sky, 30, 1-4. 
Noakes, J. E., and D. W. Hood, 1961. Boron-boric acid complexes in sea water. 

Beep-Sea Res., 8, 121-129. 
Parker, C. A., and W. J. Barnes. 1960. Fluorimetric determination of boron. 

Analyst, 85, 828-838. 
Powell, W. A., and E. H. Poindexter. 1957. 1 ,l'-dianthrimide method for the 

spectrophotometric determination of boron. Univ. Richmond, Richmond, 

Va. 41 p. 
Reynolds, R. C. and J. Wilson. 1961. Spectrochemical determination of boron in 

saline waters. Anal. Chem., 33, 247-249. 
Thompson, R. T. 1893. New aspects of phenolphthalein as an indicator. /. Soc. 

Chem. Ind., 12, 120-134. 

ACKNOWLEDGMENT The author would like to thank M. Grant Gross and T. J. Conomos for a critical 
and helpful review of this paper. I want to thank the Department of Oceanog- 
raphy, University of Washington and the Department of Geology, George Wash- 
ington University for making the necessary laboratory space available. I would 
also like to thank Janie Lochte and Doris Verhunce for typing this manuscript. 



OCEANOLOGY AND LIMNOLOGY 90 



31 



Reprinted from SCIENCE Vol. 158, No. 3803 



Deep-Sea Tides: A Program 



Walter H. Munk and Bernard D. Zetler 



Tidal mathematicians have tradition- 
ally stood along the coastlines and 
looked longingly to sea, speculating on 
what the tides are offshore. They have 
seized upon the tide records obtained 
at a few island outposts and have ex- 
pended great effort in producing co- 
tidal charts of the oceans, with lines 
connecting points at sea at which the 
time of high water is thought to be 
simultaneous. The patterns on these 
charts have been quite complex, the 
most interesting feature being the loca- 
tions of amphidromic points. These 
are the geographic positions where the- 
oretically there is no tide, the cotidal 
lines radiating about them in various 
directions, with the tidal amplitude pre- 
sumably increasing with distance from 
the amphidromic point. Inasmuch as 
the response of the ocean basins to 
the tide-producing forces is frequency- 
dependent, the more ambitious mathe- 
maticians have drawn their charts for 
each of the larae tidal constituents, both 



Dr. Munk is with the Institute of Geophysics 
and Planetary Physics, University of California 
at San Diego, La Jolla; Dr. Zetler, with the 
Institute for Oceanography, Environmental Sci- 
ence Services Administration, Silver Spring, 
Maryland. 



diurnal and semidiurnal. Despite the 
application of the best techniques and 
all available data in their efforts, specu- 
lation has been an important ingredient 
in the completed charts, and one is 
forced to the conclusion that the best 
is none too good. 

It appears as though modern technol- 
ogy has caught up with the problem 
and that there is hope of obtaining 
within a relatively few years objective 
measurements of the tide at positions 
on grids spanning the oceans. This 
is exciting in itself, but even more ex- 
citing is the anticipated solution of 
many other geophysical problems as a 
by-product of the program. 

Several different engineering groups 
are developing tide gages for deep-sea 
measurements. Snodgrass (/) has built 
a self-contained capsule that is dropped 
to the sea floor, records absolute pres- 
sure in situ, and is subsequently re- 
called by acoustic signals from a sur- 
face vessel. Some success has already 
been achieved with the instrument, but 
many failures have demonstrated need 
for greater reliability — which entails 
duplication of critical circuits, quality 
control of individual components, long 



periods of pretesting, and pretesting 
under severe environmental conditions. 
The U.S. Coast and Geodetic Sur- 
vey has made some successful meas- 
urements of the tide at depths slightly 
less than 300 meters over the Atlantic 
continental shelf; it has an active de- 
velopmental program underway to in- 
crease the depth potential of the gage 
and to improve its reliability. Martin 
Vitousek, University of Hawaii, has 
been involved in related research — the 
recording of tsunamis; although some 
problems are different in that he needs 
more frequent observations over a 
shorter period, there is significant simi- 
larity in the development program. 

The effort has not been confined 
to the United States. Eyries, Service 
Hydrographique, Paris, has successfully 
tested a differential gage that is con- 
nected by wire to a surface buoy that 
transmits an analog signal to a nearby 
vessel. The Snodgrass and Eyries gages 
also record temperature because it is 
required for correction of pressure read- 
ings, but of course the temperature 
records are of great interest in them- 
selves. Other foreign tidal authorities 
have shown marked interest in the pro- 
gram and stand ready to cooperate in 
an international program when the re- 
quired instruments become available. 

At a tide symposium (2) in Paris in 
1965, an international working group 
on deep-sea tides was formed to or- 
ganize systematic measurements and 
analyses of deep-sea tides. When the 
group met again in Moscow in 1966 
to review the program, representatives 
of 1 1 nations attended and expressed 
some interest in the program; an as- 
sociated committee (3) was formed to 
deal with theoretical problems related 



to deep-sea measurements of tides. The 
working group met again in January 
1967 (4) to participate in sea trials of 
the Snodgrass gage. Eyries organized 
the symposium on deep-sea tides 
held in conjunction with the meetings 
of the International Union of Geodesy 
and Geophysics in Switzerland during 
the fall of 1967. In short, the grow- 
ing interest in the program promises 
much for the future. 

Field tests of the Snodgrass gage so 
far have been oriented toward develop- 
ment rather than scientific results. The 
first field program for the latter purpose, 
with plans to occupy the North Pacific 
semidaily lunar (M. 2 ) amphidrome with 
three instruments, will stay on the 
bottom for 1 month. Each capsule will 
record fluctuations in the bottom pres- 
sure to the nearest millimeter of wa- 
ter; fluctuations in temperature to the 
nearest 10 -0 °C, and horizontal cur- 
rent with a resolution of 1 millimeter 
per second. If a gage is properly posi- 
tioned at the M, amphidrome, the 
M 2 amplitude will yield the continuum 
of energy rather than the tidal line; 
furthermore, the lunar semidaily tide, 
observed on either side of the amphi- 
drome, will be opposite in phase. Inas- 
much as the ocean's response is fre- 
quency-dependent, the solar semidaily 
tide (So) should exceed the A/, tide 
at the amphidrome, and the various am- 
plitudes and phases for S 2 at the 
four locations should point toward the 
probable location of the S 2 amphi- 
drome. 

Previous tests have shown an increase 
in temperature of the order of 0.05°C 
in the bottom few meters of some 
basins off the coast of California; it is 
not clear how this unstable gradient 
can persist. Furthermore, the records 
contained intermittent quiescent and ac- 
tive periods, with a time scale that is 
roughly tidal. For these reasons a 
special effort will be made to study 
bottom temperature gradients and in- 
termittent turbulence during the tests. 
One capsule is being modified to shorten 
intervals in the recording system for 
data sampling, and there will be special 
movable arms on the transducer mount- 
ing to permit careful examination of 
the bottom meter of water. A special- 
purpose winch is planned, so that the 
capsule can be lifted off the bottom 
in a predetermined program to obtain 
the vertical temperature profile to a very 
high degree of precision. Finally, a 
camera system will be incorporated to 
monitor the installation and, if pos- 



sible, observe the motions of the water 
by stereo photographs of particles drift- 
ing near the sea floor. Plans for 1968 
include an equatorial station for mea- 
suring both tides and planetary waves, 
and measurements between Australia 
and Antarctica to obtain some infor- 
mation on Antarctic tides. 

The tentative plans of the working 
group for coverage of the world's 
oceans include a 1000 by 1000-kilo- 
meter grid (10 degrees by 10 degrees 
at the equator) involving a total of 
300 stations. Measurements are to be 
made at least hourly for 1 month (cer- 
tainly for no less than 2 weeks) to 
the nearest centimeter of depth of wa- 
ter or better. Nevertheless, results from 
programs such as the North Pacific 
amphidrome test will be scrutinized 
carefully for the possibility of estab- 
lishing a variable grid, based on prelimi- 
nary theoretical results, with a maxi- 
mum of information content per unit. 
We visualize two types of expeditions 
for obtaining the tidal records: (i) ships 
of opportunity, primarily devoted to 
other purposes, dropping tide instru- 
ments on the way out and retrieving 
them on the way back; and (ii) tidal 
expeditions primarily devoted to the 
program but serving also other needs 
and opportunities. A ship should be 
able to plant eight instruments ap- 
proximately 3 days apart and then start 
to retrieve the first almost as soon as 
the planting is completed. On this basis 
eight stations are established and re- 
trieved within 2 months; since most of 
the time is spent in cruising, there is 
ample opportunity for other measure- 
ments. 

The scientific objects of the program 
include both increased understanding 
of global tides and other related geo- 
physical phenomena; the former are 
listed first: 

1) Theoretical calculations of global 
tides are now being performed by Per- 
keris and Hendershott for the true depths 
and boundaries of the world's oceans. 
So far both investigators have assumed 
perfectly reflective boundaries, but it 
appears that ultimately one must al- 
low for absorption over the continental 
shelf. The availability of an ocean- 
wide grid of tidal observations for com- 
parison with theoretical calculations will 
provide some evaluation of the need 
for a modified boundary premise; it 
will also permit reliable estimates of 
the proportion of total tidal energy 
(3 X 10 19 ergs per second) dissipated 
within the oceans. 



2) From knowledge of the global 
tides (beyond the continental shelves) 
it may be possible to infer tide predic- 
tions on a shelf for which land-based 
tide records are not available. In the 
case of highly nonlinear tides, existing 
predictions may be improved by knowl- 
edge of offshore tides; thus the non- 
linear modification may be separated 
from the astronomic tide. The dy- 
namic numerical computations will use 
depth and friction as parameters; for 
tides in rivers and bays the effective 
width will be an added parameter. Ulti- 
mately, coastal tides will be predicted 
from an initial two-dimensional tide 
"field" in the open sea. 

Although at the moment one cannot 
envisage all related geophysical objects 
of the program, the following appear 
to be possible: 

1 ) For geophysical measurements on 
land, the tidal frequencies cannot be 
interpreted without allowance being 
made for the effect of oceanic tides 
on a global basis; this point applies to 
measurements of gravity, magnetic 
field, and so on. 

2) The previous item includes cal- 
culation of the dissipation of tidal ener- 
gy in the world's ocean. The residual 
energy, 3 X 10 19 ergs per second minus 
ocean dissipation, would give important 
information concerning the plastic prop- 
erties of the solid Earth. 

3) The fluctuating tidal currents flow- 
ing in Earth's magnetic field generate 
electric potentials that can be measured 
with suitable electrodes on the sea bot- 
tom. The generated potential depends 
also on the conductivity within Earth; 
with the tides known, the effective con- 
ductivity can be estimated for various 
tidal frequencies (and hence effective 
depth). These estimates in turn give in- 
formation about the distribution of tem- 
perature in Earth's upper mantle. Hori- 
zontal temperature gradients within 
Earth, particularly beneath the ocean 
boundaries, are associated with a stress 
field that may be responsible for the 
principal belts of volcanic and seismic 
activity. 

4) Barotropic signatures of passing 
storms, which will be superimposed on 
tidal fluctuations as measured with bot- 
tom-pressure recorders, represent an in- 
teresting problem of air-sea dynamics. 
It would be especially interesting to 
have long series of simultaneous ob- 
servations of horizontal currents at 
great depth (away from surface noise). 
Planetary waves, which are so promi- 
nent in the atmosphere, have not been 



convincingly demonstrated in the 
oceans, perhaps because they are poor- 
ly generated or poorly transmitted, or 
because the observations have not yet 
measured the proper variables. Such 
measurements are simply not available 
at this time. Well-documented current 
flow near the bottom would provide a 
far better reference for geostrophic 
computations than do theoretical levels 
of no motion; estimates of mass trans- 
port could thus be significantly im- 
proved. 

5) We have already mentioned a sharp 
increase in temperature in the bottom 
few meters of the oceans. The existence 
of a warm bottom layer had been re- 
ported earlier by Van Herzen and co- 
workers from measurements with a 



geothermal probe. Is this warm layer 
maintained by greater density because 
of higher content of salt or of sedi- 
mentary particles? In fact, in the meas- 
urements of temperature gradients in 
sediments, what is. the role of tidal 
"pumping" of interstitial water? For 
these studies as well as of the intermit- 
tent turbulence, long, reliable records 
of temperature are necessary; we hope 
they will be supplemented by measure- 
ments of heat flow. 

6) Finally the observations may be 
helpful in explaining the origin of in- 
ternal waves of tidal frequencies, and, 
if tsunamis are generated during periods 
of tide observations, they may be well 
documented if the time period of the 
observations is short enough. In any 



case, the instrumental development can 
be used in a tsunami-measurement pro- 
gram. 

Thus the proposed program has ap- 
plications in much of Earth's environ- 
ment, air-sea dynamics, various ocean- 
wave phenomena, and the anelasticity 
and stress fields of the solid Earth. 
The bottom of the sea is perhaps the 
least explored of the "accessible bound- 
ary layers" on this planet, and we may 
be in for some surprises. 

References and Notes 

1. F. Snodgrass, Scripps Inst, of Oceanography, 
Univ. of California at San Diego, La Jolla. 

2. Sponsored by UNESCO and the Intern. Assoc. 
for Physical Oceanography. 

3. W. Hansen (Germany) and S. S. Voit (U.S.S.R.) 
are joint chairmen. 

4. At La Jolla, California. 



32 




Fig. 1 — Aircraft photo of eddy in the Caribbean, north of St. John, Virgin Islands. 
Such eddies aid in fishing and in weather and dynamic current studies. 

Reprinted from OCEAN INDUSTRY Vol. 2, No. 5 

OCEAN INDUSTRY DIGEST 



Fig. 2 — Daylight ESSA-1 TV photo off 



Sensing ocean currents from space 



By Raymond M. Nelson 

Institute for Oceanography, ESSA 

As part of its mission to monitor the oceans and 
study the related physical environment, the Department 
of Commerce's ESSA (Environmental Science Service 
Administration) is deeply involved in gathering basic 
data related to ocean circulation. 

Until recently, sources of such data were quite lim- 
ited, but new developments in electronics and advances 
in space technology are providing scientists with exciting 
new tools which hold great promise in this field. 

High Resolution Infrared (HRIR) Scan Imagery. An 

examination of the HRIR line scan imagery taken from 
the meteorological satellite Nimbus 2 shows that high 
thermal contrasts on water surfaces are discernible. Alli- 
son, Foshee and Warnecke of NASA and Goddard and 
Wilkerson of the Naval Oceanographic Office have col- 



laborated on the determination of water surface temper- 
atures from such data."' From the accompanying HRIR 
scan imagery and the ESSA-1 television photographs, it 
is readily apparent that surface boundaries of major 
currents can be detected and point temperature distribu- 
tions could have been measured between clouds. Time- 
sequence analyses of such quasi-synoptic coverage over 
large areas may reveal previously undisclosed surface 
circulation effects. 

EXAMPLES: Fig. 1 is an ESSA-television picture taken 
off the east coast of the U.S. on June 2, 1966 and Fig. 
3 is a Nimbus 2 HRIR photograph exposed 11 hours 
later (at night). A comparison shows the front line 
appears to have moved farther east on the infrared pho- 
tograph, and some cloud patterns, imaged near the coast 
on the infrared photograph, are not discernible on the 
Nimbus exposure. Aircraft coverage at the time of this 
Nimbus orbit proved that the local sky was free of clouds. 



40 



OCEAN INDUSTRY 




U.S. east coast, taken June 2, 1966 



Nimbus 2 HRIR photo taken of part of same area 11 hours later at night. 



An additional night-time infrared photograph (Fig. 
4 was taken September 18 and 19 off the southern tip 
of Cape of Good Hope, Africa. The white arrow points 
to the high thermal contrast of the western boundary of 
the Agulhas Current. 

What's needed to make the 
infrared system more effective? 

The system has inherent needs. The primary one is for 
surface monitoring and checking to verify the imagery. 
For example, Fisr. 5 — a Nimbus 2 HRIR photograph of 




us 2 HRIR photo off Cape of Good Hope, Africa. 




Fig. 6 — Infrared line scan photography 
of an eddy about four miles in diam- 
eter, 200 miles east of Cape Cod taken 
from aircraft. Spectral range 8-14 mi- 
crons; length of area shown is 11 
nautical miles. White spots are mal- 
functions of scanner. Light tones are 
warmer than dark tones. 

transparent convection cells over the North Atlantic 
and Gulf Stream also have been recorded. The apparent 
temperature discontinuities of such cells are only about 
1° C and the horizontal dimensions range from 1 to 10 
miles. 

What's needed for current studies? 

We know little about the meanders of the Gulf Stream. 
We are not able to predict the size, location or likelihood 
of its meanders; we do not know whether the meander 
dynamics are the same for both sides of the Gulf 
Stream. We need a multi-sensor surveillance system, 
including microwave components with cloud penetra- 
tion capability to supply raw data and surface-recorded 
data to aid us in interpretation. 

A time-sequence charting of the boundaries of sur- 
face currents as to shape size and location will contrib- 
ute much toward understanding of total dynamics and 



at the same time provide valuable data for the shipping 
industry. 

The capability of aircraft systems to detect an ocean 
eddy is illustrated in Fig. 6. Reasonably, such detection 
should be followed up by sending a ship to make a sur- 
face and subsurface profile as the aircraft is collecting 
such imagery. Themal profiles generated from micronsi- 
tometer scans across the image can be correlated with 
a ship-towed thermistor for calibration and comparison. 
Time-sequencing by the aircraft at 15 to 20-minute in- 
tervals could reveal motion within the eddy, etc. 

Exciting programs lie ahead 

The present aircraft-ship experimentation will con- 
tinue; then in the summer of 1969, the ESSA Barbados 
Oceanographic and Meteorological Experiment will be 
carried out in the eastern Caribbean vicinity. This ex- 
periment will serve as a pilot field study for the Global 
Atmospheric Research Program (GARP) of the World 
Weather Watch. It will utilize sensors ranging in heights 
from satellites down to the sea floor. 

The Tropical Meterlogical Experiment (TROMEX^ 

is scheduled for the early 1970s and some thought is 
being given to expanding it to a Tropical Environmen- 
tal Experiment. In CY 1971, the satellite systems Im- 
proved TOS, N and O and Advanced Polar Orbiting 
Satellites (APOS) A and B may carry laser altimeters 
for determining variations of sea level for geodetic 
purposes. 

An immediate measure which could contribute a 
great deal to these necessary studies would be to utilize 
"aircraft of opportunity" to fly instrument systems. 
Many airlines run over the oceans on daily schedules, 
both night and day, and the possibility of equipping 
them with sensors has a certain amount of merit. 

Basically, the ocean is an international problem, and 
the exploitation of the global surveillance capability of 
spacecraft will require international cooperation, possi- 
bly under a central cooperative control, where, as auto- 
mated data are displayed and critical changes in 
meteorological and oceanographic effects or patterns 
are detected, aircraft and ships in the area can be sent 
to monitor the region in greater detail. 

Although the needs in ocean current study technology 
are quite pronounced, a tremendous start has already 
been made. 

BIBLIOGRAPHY 

1. Stommel, H. M., W. S. Von Arx, D. Parson, and W. S. Richardson, 
"Rapid Aerial Survey of Gulf Stream with Camera and Radiation Ther- 
mometer," Science, 1953, 117:639-640. 

2. McAlister, E. D., "Infrared-Optical Techniques Applied to Oceanog- 
raphy: 1 Measurement of Total Heat Flow from the Sea Surface," Applied 
Optics. 3, pp. 6U9-612, 1964. 

McAlister, E. D. and McLeish, W. L., "Oceanographic Measurements 
with Airborne Infrared Equipment and Their Limitations," Oceanography 
from Space, Woods Hole Oceanographic Institution, Woods Hole, Mass., 
pp. 189-214. April 1965. 

3. Ewing, Dr. G. C., "The Use of Film as a Sensor," Minutes of the 
Fourth Meeting Ad Hoc Spacecraft Oceanography Advisory Group, Space- 
craft Oceanography Project, U. S. Naval Oceanographic Office, 18-19 Oc- 
tober 1966, p. 12. 

4. NASA, Goddard Space Flight Center, (Private Communication). 

5. Allison, L. J. L. L. Foshee, G. Warnecke, and J. C. Wilkerson, "An 
Analysis of the North Wall of the Gulf Stream Utilizing Nimbus 2 High 
Resolution Infrared Measurements," Gulf Stream Symposium, American 
Geophysical Union, April 17-21, 1966. 

6. Oshiver, A. H., G. A. Berberian, J. R. Clark and R. B. Stone. "Far- 
tors in Measurement of Absolute Sea Surface Temperature by Infrared 
Radiometry," University of Michigan, Ann Arbor, pp. 737-762, February 
1965. 

7. Clark. H. (Private Communication), U. S. Naval Research Laboratory. 
Applied Oceanography Branch, Washington, D. C, "Clear Air Convection 
Cells," March 1967. 

8. Smith, J., "Color — A New Dimension in Photogrammetry," Photo- 
grammetric Engineering, Nov. 1963. Fig. 7. pp. 999-1013. ■ 



42 



OCEAN INDUSTRY 



33 



Reprinted from TRANSACTIONS-SECOND INTERNATIONAL BUOY 
TECHNOLOGY SYMPOSIUM, The Marine Technology Sooiety 

-Jt AN OCEANOGRAPHIC DATA COLLECTION SYSTEM 



P. E. Seelinger, R. A. Walls ton, 
B. H. Erickson, 1 J. E. Masterson, 2 W. E. Hoehne 3 

Pacific Missile Range 
Point Mugu, California 



ABSTRACT 



A buoy system was designed and installed to provide meteorological and 
oceanographic data to support surface, aircraft, rocket and missile test 
operations off the southern California coast. This system measures wind 
speed and direction, air temperature, barometric pressure, sea surface tem- 
perature, and wave height. The system also measures subsurface temperature, 
current speed , and current direction at various depths . The data are 
stored in the buoy and transmitted on command to a shore station, where 
they are recorded for reduction by a computer. 

The buoy assembly consists of a surface float connected to a subsurface 
buoy at a depth of 50 feet. The subsurface buoy is taut -moored to the bot- 
tom. Meteorological sensors are mounted on the mast of the surface float. 
The recording, digitizing and telemetry equipment are within the surface 
float. A wave height sensor is mounted on top of the subsurface buoy. Cur- 
rent meters and water temperature sensors are attached to the taut mooring 
cable. 

One buoy assembly was moored on 3 September 1966, and gathered and trans- 
mitted data for about seven months . The reliability and accuracy of the 
sensors during this period were judged good. The overall performance of 
the buoy assembly demonstrated its potential usefulness in providing envi- 
ronmental data affecting Sea Test Range operations. 

INTRODUCTION 

In testing and evaluating bomb, missile and rocket systems, it is necessary 
to have accurate knowledge about the environment in which the tests are 
conducted. Sea state and currents, for example, affect water entry tests 
and the recovery of missile components from the sea. Wave height spectra 
provide information on radar sea clutter for evaluating radar-guided mis- 
sile performance. In addition, accurate data are essential in order to 
forecast oceanographic and meteorological conditions in and over the test 
range. 

Required oceanographic information is normally obtained from subjective 
estimates made by shipboard and airborne observers, and from analyses of 
weather charts . Some information is extrapolated from measurements 



1. Present affiliation: Pacific Oceanographic Laboratory, Institute for 
Oceanography, ESSA, Seattle, Washington. 

2. Present affiliation: National Center for Atmospheric Research, Boulder, 
Colorado . 

3. Present affiliation: Weather Bureau, System Development Office, ESSA, 
Sterling, Virginia. 



311 



provided by snore-based equipment — e.g. , wave staffs and oottom-mounted 
wave meters. A smaller amount of data is obtained irregularly from portable 
instruments — e.g. , buoy -mounted wave staffs and bathythermographs. 

The buoy system described in this paper was designed to obtain continuous 
oceanographic and meteorological data at sites where water depth does not 
exceed 3,600 feet (600 fathoms) and the data transmission distance is not 
greater than 60 nautical miles. Sea surface and subsurface data, particu- 
larly of wave height and period , were the primary requirements . Specifi- 
cations for meteorological data were included to make fullest possible use 
of the surface float platform and assembly. Table 1 lists the variables to 
be measured. 



Table 1 
ENVIRONMENTAL VARIABLES TO BE MEASURED 



Category 


Measurement 


Meteorological 


Wind speed and direction 
Air temperature 
Atmospheric pressure 


Sea surface 


Water temperature 
Wave height and period 


Subsurface 


Current speed 
Current direction 
Water temperature 



A preliminary survey of existing buoy assemblies, sensors, and instrumenta- 
tion had revealed that equipment and techniques were sufficiently developed 
to permit their integration into a system. A number of contractors judged 
qualified on the basis of past experience in the design and installation of 
buoy systems were asked to submit two-step technical proposals . Five out 
of nine completed proposals ; and the contract for design and delivery of the 
system was awarded to the Bissett-Berman Corporation of Santa Monica, Cali- 
fornia (1). A separate contract covered installation of the first buoy 
assembly. The government provided most of the standard components of the 
shore station, as well as programming and computer facilities at the PMR 
Weather Center. 

The buoy assemblies are instrumented to take measurements of the environ- 
mental variables shown in Table 1, and transmit them on command to a shore 
station for computer processing. These synoptic data are then analyzed 
every 6 hours to provide information about sea and weather conditions in 
specific test areas, and in detail not obtainable by other means. 

The area considered for installation of the buoy system includes the PMR 
Sea Test Range and is shown in Figure 1. It lies among the Channel Islands, 
east of Santa Cruz Island and north of San Nicolas Island, within the 
continental borderland — a region of basins , troughs , shallow banks , 
islands, and minor shelves off the islands. Five sites (Figure 1) were 
surveyed as possible locations for buoy assemblies; and Site #2 was selected 
for installation of the first buoy assembly. 

This paper will first describe the buoy system design and the data-handling 
subsystem. It will then cover the survey and installation procedures. 
Finally, it will evaluate the data obtained during feasibility tests of one 
buoy assembly. 



312 



SYSTEM DESIGN 

The Oceanographic Data Collection System (ODCS) was designed to consist of 
four buoy assemblies, installed at four of the five proposed sites (Fig- 
ure 1). Each buoy assembly was to be equipped with appropriate sensors, 
a data-handling subsystem, a telemetry receiver and transmitter, power 
supply and antenna. Data would be received at the shore station and stored 
for later processing by computer. One of the four buoy assemblies was in- 
stalled as a "shakedown" in order to test overall performance and solve 
working system problems before implementing the total system. 

Buoy Assembly 

The buoy assembly shown in Figure 2 consists of a surface float slack- 
moored to a subsurface buoy at a depth of 50 feet. The subsurface buoy is 
taut -moored to the bottom by a 3/8-inch steel cable strain member attached 
to a shaped anchor clump weighing about 2,500 pounds. A separate Danforth 
anchor gives further assurance against movement along the bottom. Two 
mechanical swivels, one just above the anchor and the other below the lowest 
sensing instrument, keep the assembly from twisting. Separate data trans- 
mission cables are attached to the strain cable, but carry no strain. A 
system of watertight connectors in the electrical cables allows for replace- 
ment of individual sensor pods (by divers) at levels down to 150 feet. The 
entire assembly with the exception of the anchor is designed to be recovered 
by activating an acoustic release device, located just above the anchor. 

The surface float shown in Figure 3 is a steel-covered discoid 10 feet in 
diameter. Compartments in the center contain the electronic equipment , 
packaged individually in modular watertight containers , and are surrounded 
by compartments filled with polyurethane foam. A 13-foot quadrapod mast 
carries the antenna, the meteorological instruments, and the radar reflec- 
tors , navigation light and bell . 

The subsurface buoy shown in Figure M- is a cylindrical tank 8 feet long and 
4 feet in diameter. It is constructed of 12-gauge steel, weighs approxi- 
mately 800 pounds, and has a net buoyancy of approximately 2,000 pounds. 
The wave height and water temperature sensors are housed together in a steel 
case on top of the buoy. Mounted near the sensors is a battery-operated 
pinger, which turns on automatically if the electrical cable to the surface 
buoy is disconnected or severed. The device thus assists in locating the 
subsurface buoy if the surface float breaks free. 

Sensors 

Figure 5 shows the meteorological sensors mounted on the quadrapod mast 
approximately 10 feet (3 meters) above the mean water line. The sensors 
include instruments to measure wind speed, wind direction, air temperature 
and barometric pressure. 

The oceanographic sensors are mounted at various positions along the taut 
mooring cable as well as on the subsurface buoy and surface float. Water 
temperature, current speed and current direction sensors (Figure 6) are 
attached to the mooring cable at 75, 150, and 500 feet below the surface. 
Another water temperature sensor is moftnted, with the wave height sensor, 
on the subsurface buoy, at a depth of 50 feet (Figure 7). The sea-surface 
temperature sensor protrudes through an opening in the bottom of the surface 
float at a depth of about 3 feet. 

Table 2 lists the meteorological and oceanographic variables and the instru- 
ments used to measure them. It also describes the range and accuracy of 
each sensor. 



313 



Table 2 

INSTRUMENTS USED TO MEASURE 
METEOROLOGICAL At© OCEANOGRAPHIC VARIABLES 



Variable 


Instrument 


Range 


Accuracy 


Wind speed 


3-Cup anemometer 


2 to 99 kn 


+ 5% true 


Wind direction 


Wind vane 


to 360° 


+ 10° true 


Air temperature 


Thermistor 


to 40°c 


+ 0.2°C 


Barometric 


Aneroid barometer 


950 to 1049 mb 


+ 1.0 mb 


pressure 








Wave height and 


Pressure transducer 


0.5 to 16 ft 


+0.1 psi 


period 




5 to 25 sec 




Sea water 


Thermistor 


to 30°C 


+ 0.2°C 


temperature 








Current speed 


Savonius rotor 
current meter 


0.05 to 6.0 kn 


± 3% true 


Current 


Current meter vane 


to 360° 


+ 10° true 


Direction 









The sensors were not intended for use in research and development; and in 
most cases, off-the-shelf instruments were adequate to system needs. The 
wind sensors, however, were modified considerably to withstand the marine 
environment. All the sensors were calibrated before installation. The 
accuracies indicated in Table 2 were met , and calibration curves for each 
sensor were made and provided to the Navy at Point Mugu. No further cali- 
bration tests on the sensors were conducted after the buoy assembly was 
installed in the open sea. However, some comparative observations were 
made when possible; and these are discussed in a later section of the paper. 

The Data -Handling Subsystem (DHS) . The DHS on board the surface float 
controls the acquisition, storage, and transmission of data from all the 
sensors . Figure 8 is a block diagram of how the total system functions . 
Interrogation of the sensors is initiated at 20-minute intervals by the 
system timing and control logic circuits. All the sensors are scanned 
sequentially within a period of a half-second by the commutator. The 
analog voltages from the sensors are converted into digital information by 
the A/D converter. These data are then stored in the core memory, which 
has a capacity of about 15,000 bits. The wave height data consist of 
samples taken at 2-second intervals for a period of 20 or 40 minutes once 
every 6 or 12 hours respectively. 

The upper portion of the block diagram (Figure 8) represents the shore 
station system. A clock timer may be pre-set to interrogate the buoy 
automatically at specific times — or the buoy may be interrogated manu- 
ally. In either case, a two- tone command is sent to the buoy to start 
transmission of the data stored in the core memory. Information from the 
buoy is transmitted in binary code, using standard 100 word-per-minute 
teletype format. The signals are received at the shore station, where the 
data are recorded in 5- level teletype code on punched paper tape. The 
data on the tape are later processed by a Control Data Corporation 3100 
computer. Specifications for the EHS are shown in Table 3. 



314 



Table 3 
SPECIFICATIONS FOR DATA-HANDLING SUBSYSTEM 



Data input 


16 analog channels 


Range 


0-511 millivolts 


Data sampling period: 
Channels 1-15 
Channel 16 


600 milliseconds total 
180 milliseconds 


Data sampling rate: 
Channels 1-15 
Channel 16 


every 20 minutes 

every 2 seconds ( Channel 
16 is activated either 
every 6 hours for a 20- 
minute period or every 
12 hours for a 40 -minute 
period, depending on 
the switch position se- 
lected. ) 


Data storage capacity 


15,232 bits 


Storage requirements : 
Channels 1-15 

Channel 16 — 20-minute sample 
40-minute sample 


170 bits (including buoy 

ID and time code) 
6,000 bits 
12,000 bits 


Digitizer accuracy 


± 2 millivolts 


Data output 


teletype format 


Data rate 


10 characters per second 


Data readout period 


5 minutes and 6 seconds 



Figure 9 shows the actual shore installation at Point Mugu, which is con- 
tained in essentially one rack of equipment. It includes the receiver, 
clock timer, encoder, demodulator, and paper tape punch. The command 
transmitter, located at another site, is remotely controlled. 

Data Reduction . The data sto»ed on the punched tape are reduced by the 
computer. The processing accomplishes the following: 



1. Edits the data for proper sensor-scan format, and locates 
and separates wave height data 

2. Converts the binary numbers representing millivolt values 
to engineering units 

3 . Determines 20-minute average current speeds and wind speeds 

4. Converts time code to Greenwich mean times (time of interro- 
gation is an input for each tape) and determines starting 
times of wave height samples 



5. Lists both raw and processed data. 



315 



A separd /ave height program edits the individual pre e measurements 
and then determines a power spectrum to find the contribution of each wave 
period to the pressure variations measured at depth. The contribution of 
each period is then multiplied by the factor which describes its attenu- 
ation with depth. Finally, the pressure variations are converted to feet, 
the contributions of all periods summed, and the wave heights calculated 
in accordance with Pierson, Neumann and James (2). In actual practice, the 
data are separated into four groups and an average taken. 

Figure 10 shows a listing of processed data in the format produced by the 
computer. These data were received from the buoy on 21 February 1967 at 
1120Z. 

SITE SURVEY AND INSTALLATION OF BUOY ASSEMBLY 

Before installing a taut -moored buoy system, it is necessary that rather 
accurate surveys of prospective sites be made. Five sites within the Sea 
Test Range were selected, varying in depth from 1,680 to 2,880 feet. 
Bathymetric surveys of each of the five sites were conducted to measure 
depths and determine the configuration of the sea floor. Two-inch gravity 
cores were taken to determine bearing properties of the sea floor. Current 
profiles were also measured at each of the sites . LORAC B was used for 
navigation during both the survey and installation. 

The four sites best suited for installing the four buoy assemblies of the 
complete system were specified. Site #2 (Figure 1) was selected for in- 
stalling the first buoy assembly and conducting the feasibility tests. 
Water depth at Site #2 was 2,562 feet. Bottom topography insured that the 
buoy would not be located on a steep incline; and the sediment sample indi- 
cated that anchor slippage would be minimal. 

The M. V. Ceylon and a buoy boat were used to install the buoy assembly. 
The complete buoy assembly was laid out on the deck of the Ceylon . The 
surface float, subsurface buoy, and electrical and mechanical cabling were 
arranged in such a way that the entire assembly could be checked out and 
installed as a complete unit. 

Figure 11 shows how the assembly was distributed at the mooring site. The 
surface float was lowered into the water. Rubber floats were attached at 
various positions along the assembly so that as the surface float was towed 
away from the Ceylon by the buoy boat, the entire assembly was distributed 
on the surface of the water. All sensors, transmitters and system compo- 
nents were checked out and monitored as they floated on the surface. Loca- 
tion position was maintained by the LORAC B. The rubber floats were 
released and the anchor finally lowered to swing the taut -moor assembly 
into place. Divers made final checks on all equipment and sensors to a 
depth of 150 feet; and a final transmission check was conducted with the 
shore station at Point Mugu. 

DATA EVALUATION 

The ODCS buoy assembly was installed on 3 September 1966 and remained 
moored for about 7 months. After 3 months of service, an improved mechani- 
cal connector was installed at the surface float. Despite interruptions 
for various equipment failures , sufficient data of reasonable accuracy were 
obtained during the 7-month period to demonstrate the feasibility and value 
of the system. 

When possible, the processed buoy sensor data were compared with measure- 
ments obtained by on-site observations and from meteorological instruments 
on San Nicolas Island, Santa Cruz Island, and at Point Mugu. When these 
comparisons were made, the processed data were generally found to be 



316 



reliable and ao_ ate. Examination of large discrepancies in v data 
usually disclosed problems that could be attributed to the cabling rather 
than to the sensors themselves. Table 4 shows some typical comparisons of 
observer and buoy measurements for a few variables. 



Table 4 
COMPARISON OF OBSERVER AND BUOY MEASUREMENTS 





1 October 


5 November 


18 December 




Observer 


Buoy 


Observer 


Buoy 


Observer 


Buoy 


Wind speed 
Air temperature 
Water temperature 


6-8 kn 
65.8°F 
66.2°F 


5 kn 
66.4°F 
67.8°F 


8 kn 
60.0°F 
63.0°F 


9 kn 
59.4°F 
62.9°F 


2 kn 
59.3°F 
59.3°F 


4 kn 
59.6°F 
59.1°F 



Comparative data on wind speed and direction are often difficult to evalu- 
ate. Synoptic surface weather charts permit only broad comparisons with 
data obtained at a particular buoy location. Hand-held anemometers are 
not very accurate; and when an observer is standing on the deck of a small 
boat , measurement accuracy further deteriorates . Nevertheless , measure- 
ments of wind direction and speed from boats near the installation site 
compared well with the data transmitted by the buoy sensors. 

Air temperature telemetered by the buoy was within one degree of the tem- 
perature as measured from service boats visiting the site. Throughout the 
operational test period, buoy measurements of air temperature were reason- 
ably accurate, generally within one degree of the reported temperature in 
the area. 

Continuous comparisons were made of mean barometric pressures at Point Mugu 
and San Nicolas Island with the pressures telemetered from the buoy. At 
first, large and erratic differences were noted. The sensor was replaced, 
and subsequent buoy readings showed minimal differences from the mean pres- 
sures at San Nicolas and Point Mugu. The small consistent bias in the buoy 
data could easily be adjusted. Hence, the measurements were considered 
reliable and accurate. 

A few wave height measurements from the buoy were compared with subjective 
observations made on service boat visits to the buoy and with synoptic maps. 
The original circuit for the wave height sensor on the subsurface buoy did 
not permit production of usable data. Once this circuit was modified, how- 
ever, buoy measurements compared well with subjective observations from 
the boat. Wave height measurements from the buoy also compared well with 
calculations based on wind velocity and fetch as shown on the synoptic 
weather maps of the area. 

On one occasion, wave heights were measured at the buoy site with a free- 
floating buoy -mounted wave staff, called an Ocean Wave Profile Recorder 
(OWPR). As shown in Table 5, measurements from the buoy generally under- 
estimated the wave heights. However, a recent correction of a procedural 
error in the computer program is expected to eliminate this bias. 



317 



Table S 



COMPARISON OF COMPUTED SPECTRA OF WAVE HEIGHT DATA 



(8 FEBRUARY 


1967, 1115 PST) 






Buoy 


OWPR 


Most frequent 




0.5 ft 


0.6 ft 


Average 




0.6 ft 


0.7 ft 


Average of 1/3 highest 




1.0 ft 


1.2 ft 


Average of 1/10 highest 




1.2 ft 


1.6 ft 



Sea-surface water temperatures were compared with bucket observations made 
on service visits to the buoy. Differences were within the allowed accu- 
racy range. 

Subsurface temperatures measured by the buoy sensors were compared with 
readings from expendable bathythermographs. On 20 October 1966, a record was 
taken from a bathythermograph (BT) located within one-half mile of the buoy. 
The purpose of visiting the buoy at that time was to inspect the faulty tem- 
perature sensor at the 150-foot depth. The buoy readings at this depth, as 
shown in Table 6, reflect the instrument failure. The temperatures at the 
other depths , however , were within the accuracy requirements when compared 
with the BT values. 



Table 6 

COMPARISON OF SUBSURFACE TEMPERATURES 

(20 OCTOBER 1966) 





Temperature 


in Degrees Centigrade 


Depth in feet 


Buoy 

1120 PDT 


Buoy 
1140 PDT 


Expendable BT 
1130 PDT 


50 


17.22 




17.22 


17.1 


75 


16.74 




16.74 


16.6 


150 


18.00 




18.00 


13.7 


500 


9.66 




9.66 


9.5 



No comparisons of current speed or current direction data were made during 
the operational period. However, measurements at the 75- and 150-foot 
depths seemed reasonable when compared with earlier current observations 
made during the survey runs. 



318 



d^ 



SUMMARY AND CON^ JONS 

During the 7 months that the buoy assembly was moored, the processed sensor 
data were generally reliable. The meteorological data were periodically 
compared with independent observations, and were found usually to be within 
the accuracy limits specified for the sensors. Initially, the barometric 
pressure sensor caused problems ; but after it was replaced , pressure data 
from the buoy compared well with barometric pressures recorded at San Nico- 
las Island and Point Mugu. The oceanographic measurements were also gener- 
ally reliable and accurate. The wave height sensor as originally installed 
was not sufficiently sensitive; however, the problem was corrected, and 
subsequent data transmissions were judged reasonable. 

During this operational test or "shakedown" period, transmission of data 
was not continuous . Interruptions were caused , for example , by radio 
interference and by cabling and connector problems. When equipment prob- 
lems occurred, the buoy often could not be serviced for days because of 
missile test operations in the area. Figure 12 shows the number of trans- 
missions possible, the number of transmissions actually received, and the 
number of good or reasonable measurements recorded. A good or reasonable 
measurement is defined as one that is consistent with previous and subse- 
quent measurements and with the synoptic situation, and also compares well 
with measurements made by other means . 

The ratio of transmissions received to the number possible was rather low. 
The ratio of good measurements to the number of transmissions received, 
however, was much higher — and improved towards the end of the 7 -month 
period. Of the total number of transmissions possible (assuming no system 
failures or radio interference), approximately 33 per cent were received. 
Of the number received, approximately 80 per cent were considered reason- 
able or good data. 

Transmission failures were due to causes which can be grouped into four 
general categories: problems with buoy assembly components (53 per cent); 
radio interference and atmospheric noise ( 30 per cent ) ; failures in shore 
station components (13 per cent); and miscellaneous problems (4 per cent). 

Most of the difficulties with the buoy assembly involved the cabling and 
connectors , especially when they affected a power supply to several sen- 
sors. A problem with one cable would then cause distortions in several 
other sensor readings. A circuit modification was later incorporated into 
the system to overcome these difficulties . 

The problem of radio interference was also substantial. Heavy interference 
with the buoy signal at night and in the early morning resulted in the 
loss of most nighttime and early morning data. This emphasizes the impor- 
tance of thorough preliminary examination of frequencies and propagation 
conditions to insure good reception of data and minimize interference. 
Loss of data, then, was caused primarily by cabling problems and interfer- 
ence , rather than by difficulties with the sensors . The meteorological 
and oceanographic sensors generally were reliable and provided good measure- 
ments. 

Some anticipated problems never materialized. It was expected that diffi- 
culties might occur with the mooring and with deterioration of the sensors 
and buoy components. The mooring, especailly the taut portion, performed 
better than anticipated. During the operational test period, at least two 
major storms passed over the area: the surface float sustained winds of 30 
to HO knots for 12 hours or longer; and the entire assembly withstood the 
attendant sea conditions. It was only after 7 months of operation that 
the slack moor parted near the lower end; radar surveillance showed that 
the buoy had gone adrift on 2 April 1967. The surface float was recovered 



319 



on 7 Aprf The sensors, surface float, and navigation/ juipment shewed 
only modfe. _ L e deterioration from exposure to the sea ana ..rather. 

Another anticipated problem was that of vandalism and wanton destruction 
of the buoy or its components. The buoy assembly was in an area frequented 
by fishing boats and pleasure craft, but no such problem developed. 

Although the buoy assembly as tested has some problems, none of them is 
severe enough to change the basic system or invalidate its use for obtain- 
ing oceanographic and meteorological data. The design and construction 
of the assembly are basically sound. Its performance during 7 months of 
operation and testing showed that taut -moored buoys can function well over 
an extended period of time and provide reliable data not obtainable by 
other means. 

For a buoy assembly more remote than the ODCS, the use of an environmental 
data collection and/or communication satellite system should be considered. 
A low-orbiting satellite, for example, could interrogate, store, and trans- 
mit data from numerous buoy arrays to a data collection and processing 
center. Or, a synchronous satellite system could serve for collection and 
communication of data from buoy arrays to such a central facility. In 
these and other ways , the basic buoy system described in this paper might 
be further developed or modified to meet the needs for more extensive col- 
lection of measurements of meteorological and oceanographic variables. 

ACKNOWLEDGMENTS 

The authors gratefully acknowledge the assistance and support of personnel 
of the Geophysics Division during the buoy evaluation and operational test 
periods. We are particularly indebted to Mr. T. R. Carr and to LCDR 
John D. Hague, USN, for their constant interest and valuable support. 
Mr. Frederick G. Roehler II was most helpful in electronic and mechanical 
analysis, as was Mr. Stevens K. Okura in the data analysis and programming 
phase of the tests. 

REFERENCES 

1. Denton, R. F. , and P. C. Stahl, 1967: "Concept and Design of the SEAS 
Buoy System, Trans . 3rd Annual Marine Technical Society Conference and 
Exhibit, 5-7 June 1967, 1+93-501. 

2. Pierson, W. J., Jr., G. Neumann, and R. W. James, 1955: "Practical 
Methods for Observing and Forecasting Ocean Waves by Means of Wave Spectra 
and Statistics," U.S. Navy Hydrographic Office Publication No. 603, 284 pp. 



320 










321 




FIGURE 2. The buoy assembly consists of the surface float, the sub- 
surface buoy, the anchor, the sensors, and the strain and 
electrical cables. 



322 



■i 



ANTENNA 



BELL 




LIGHT 



METEOROLOGICAL 
SENSORS 



RADAR 
REFLECTORS 



FIGURE 3. The surface float contains the electronic 
equipment and power supply — and supports 
the mast carrying the meteorological and 
navigational instruments . 



323 




WAVE HE5GHT & WATER 
TEMPERATURE SENSORS 




FIGURE l +. The subsurface buoy, a cylindrical tank, carries 
the wave height and water temperature sensors. 



824 



AIR TEMPERATURE 



WIND DIRECTION 




FIGURE 5. The meteorological sensors are mounted on the quadrapod mast. 



325 





FIGURE 6. The oceanographic sensors measure water temperature, 
current speed, and current direction. 



326 




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FIGURE 9. The shore installation consists essentially 
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329 



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LIST OF FIGURES 

FIGURE 1. Five sites were surveyed. Site #2 was selected for installa- 
tion of the first ODCS buoy assembly. 

FIGURE 2. The buoy assembly consists of the surface float, the sub- 
surface buoy, the anchor, the sensors, and the strain and 
electrical cables . 

FIGURE 3 . The surface float contains the electronic equipment and power 
supply — and supports the mast carrying the meteorological 
and navigational instruments. 

FIGURE 4. The subsurface buoy, a cylindrical tank, carries the wave 
height and water temperature sensors . 

FIGURE 5. The meteorological sensors are mounted on the quadrapod mast. 

FIGURE 6 . The oceanographic sensors include instruments to measure water 
temperature, current speed, and current direction. 

FIGURE 7. A water temperature sensor and the wave height sensor are 
mounted on the subsurface buoy at a depth of 50 feet. 

FIGURE 8. The Data-Handling Subsystem, within the surface float, con- 
trols the scanning, conversion, storage, and transmission 
of data from all the sensors . The shore station system ini- 
tiates telemetry, encodes the signals, and punches the data 
on paper tape for processing by the computer. 

FIGURE 9 . The shore installation consists essentially of one rack of 
equipment . 

FIGURE 10 . A typical data printout shows the format in which data are 
produced from the computer. 

FIGURE 11. The buoy assembly was distributed on the surface of the water 
at Site #2. Location position was maintained by 
the LORAC B. The anchor was finally lowered to swing the 
taut -moor assembly into place. 

FIGURE 12. The chart shows the number of transmissions possible, the 

number of transmissions actually received, and the number of 
good or reasonable measurements recorded. 



333 



NVO-235-2 



HIG-67-11 



34 



LOW-FREQUENCY WAVE STUDY 
IN THE MESO-DEEP OCEAN 



By 

MARTIN J. VITOUSEK 

Hawaii Institute of Geophysics 

and 

GAYLORD R. MILLER 

Environmental Science Services Administration 



Prepared for 

U.S. ATOMIC ENERGY COMMISSION 

NEVADA OPERATIONS OFFICE 

SUPPLEMENTARY PROGRAM 

AEC CONTRACT AT(26-1)-235 



FINAL REPORT 
JULY 1967 



HAWAII INSTITUTE OF GEOPHYSICS 

UNIVERSITY OF HAWAII 




NVO-235-2 



HIG-67-11 



LOW-FREQUENCY WAVE STUDY 
IN THE MESO-DEEP OCEAN 



by 



Martin J. Vitousek 
Hawaii Institute of Geophysics 

and 

Gaylord R. Miller 
Environmental Science Services Administration 



Prepared for 

U. S- Atomic Energy Commission 
Nevada Operations Office 
Supplementary Program 
AEC Contract AT(26-l)-235 



FINAL REPORT 
July 1967 



Approved by Director 
Date: 12 July 1967 




LEGAL NOTICE 



This report was prepared as an account of Government 
sponsored work. Neither the United States, nor the 
Commission, nor any person acting on behalf of the Commission: 

A. Makes any warranty or representation, ex- 
pressed or implied, with respect to the accuracy, 
completeness, or usefulness of the information con- 
tained in this report, or that the use of any information, 
apparatus, method, or process disclosed in this report 
may not infringe privately owned rights; or 

B. Assumes any liabilities with respect to the use 
of, or for damages resulting from the use of any infor- 
mation, apparatus, method, or process disclosed in this 
report. 

As used in the above, "person acting on behalf of 
the Commission" includes any employee or contractor of 
the Commission, or employee of such contractor, to the 
extent that such employee or contractor of the Commission, 
or employee of such contractor prepares, disseminates, 
or provides access to, any information pursuant to his 
employment or contract with the Commission, or his employment 
with such contractor. 



TABLE OF CONTENTS 

Page 

INTRODUCTION 1 

THE SENSORS 2 

THE CABLE 2 

SHORE ELECTRONICS 3 

INSTALLATION DETAILS 3 

ENVIRONMENT AND EXPOSURE 4 

TRANSDUCER CALIBRATION 5 

CONCLUSION 5 

REFERENCES 6 



ill 



INTRODUCTION 



The objective of this research was to install and maintain instru- 
mentation for recording low-frequency waves in deep water off the Kona 
coast of the island of Hawaii. The signals were to be presented to 
the existing AEC data-acquisition system for recording. To the date of 
this report, this objective has been achieved. 



Timetable 



The factor governing the installation timetable was cable delivery. 
The specially manufactured cable arrived in Hilo on January 31, 1967. 
On the next day, February 1, the Keauhou cable and transducer were 
laid at a depth of 90 fathoms at 19°33.5 f N, 156°00.0'W. On February 2 
the Airport cable and transducer were laid at a depth of 288 fathoms at 
19°37.9'N, 156°02.3'W. The following week was spent securing the cable 
shore ends and constructing suitable hetrodyne frequency sources to 
beat with the final measured signals from the installed Vibrotrons 
that would meet the input frequency requirements of the AEC system. 
Precision crystal sources at the appropriate frequency were also ordered 
at this time. The Vibrotron center frequency of the Keauhou gage is 
10,055 Hz and that for the Airport gage is 18,765 Hz. 

On February 11 the Airport system became operational employing as 
a hetrodyne frequency source the 192nd harmonic of the precision 100 cps 
output of a Hewlett-Packard Model 4243L Counter. A Hewlett-Packard 
Model 302A Wave Analyzer was employed to filter out this harmonic. 

On February 14 the Keauhou system became operational employing the 
fourth harmonic of a tuning fork as a hetrodyne frequency source. This 
source was lower than the Vibrotron frequency causing an inversion of the 
output, i.e., increasing frequency indicated decreasing water level. 

During the period February 11 to May 7, two interruptions of signal 
were experienced at the airport. The cause, discovered after the second 
interruption, was improper output from the wave analyzer resulting from 
general power failures. After a power failure the wave analyzer would 
lock onto the 193rd harmonic, causing the mixer output to be too high to 
pass through the 400 Hz bandpass filter. No interruptions were experienced 
at Keauhou. 



-1- 



-2- 



On April 7 the two permanent precision frequency sources were in- 
stalled. The outputs were now centered at about 400 Hz and, for both 
gages, increasing frequency indicated increasing water depth. No further 
interruptions have occurred to date. 



THE SENSORS 



The sensing units are Vibrotron pressure transducers (Vitousek, 1965) 
The diaphragms of these transducers are exposed directly to sea pressure 
through an oil-sea interface. They are isolated from environmental 
temperature changes by a 5-inch layer of bees wax which has a thermal 
time constant of over one hour (Fig. 1). Two Vibrotron amplifiers are 
provided for each Vibrotron so that should one fail, the other is 
activated by reversing polarity on the cable (Fig. 2). The Vibrotrons 
and associated amplifiers are enclosed in a stainless steel pressure case 
two inches in diameter and twelve inches long. The case is in turn 
imbedded in axle grease in the center of a cylinder of bees wax twelve 
inches in diameter and three feet long, which is encased in a twelve- 
inch PVC pipe (Fig. 3). The pipe is equipped with three cable clamps 
on one side and a twenty-five-pound lead weight on the other. The lead 
is attached to the pipe with PVC bolts so that nowhere are dissimilar 
metals in electrical contact. A three-hundred PSIA Vibrotron is used 
for the ninety-fathom installation and a seven-hundred and fifty PSIA 
Vibrotron for the two hundred and eighty-eight fathom installation. The 
Vibrotron pressure ports are connected to the sea through oil-filled 
nylon tubing which terminates in copper sleeves to retard fouling. 



THE CABLE 



A special cable was ordered for this installation based on a 
successful experience with similar cable on another project. As the 
electrical requirements were minimal, a steel conductor was employed to 
increase reliability and decrease cost. The conductor consists of a 
3/8-inch, 7-wire galvanized steel strand, which had an asphalt-base 
flooding compound applied during the stranding operation to prevent water 
entering the interstices should a leak occur. Two passes of black high- 
density polyethylene insulation were then applied, the second pass was 
used to cover any possible pin holes in the first pass. The insulation 
was then covered by a 16-strand spiral-wrap layer of galvanized steel wire 
to furnish approximately a 95 percent coverage. This armor was then 
covered by an outer jacket of black high-density polyethylene. The 
cable has a finished diameter of 11/16 inch, a weight of 0.5 lb/foot, 




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and an electrical loop resistance of five ohms per thousand feet. The 
cable was supplied on drums containing 20,000 feet of cable at a cost of 
25 cents per foot. At the shore end of the 90-fathom transducer the 
sea cable is connected directly to the shore electronics at the head of 
Keauhou Bay (Fig. 4). For the deeper transducer the cable emerges 
from the ocean approximately one mile from the recording hut (Fig. 5). 
A small line amplifier is installed at this point and standard RG 59 U 
cable is employed for the remainder of the run to the recording hut, 
which is located at the Kona Airport. 



SHORE ELECTRONICS 



On shore the Vibrotron signal is amplified and hetrodyned against 
a highly stable signal, 200 Hz or 400 Hz above the Vibrotron signal 
(Fig. 6). For the 90-fathom transducer a hetrodyne frequency of 200 Hz 
is used, and the output of the mixer is doubled to 400 Hz. For the 
288-fathom transducer the hetrodyne frequency is 400 Hz higher than 
the Vibrotron frequency. The hetrodyne frequency is derived from a 
crystal oscillator in a proportionally controlled oven. After passing 
through a lowpass filter the 400-Hz signals are delivered to the AEC 
telemetry system. 



INSTALLATION DETAILS 



The 90-foot University of Hawaii research vessel TERITU was used 
to lay the cable. The transducers were attached to the cable using 
the three 3/4-inch cable clamps. The center cable conductor was 
swaged to a short length of bare 3/8-inch #16 copper wire using a 
3/8-inch Nicopress sleeve. A 1/4-inch Nicopress sleeve was used to 
swage half of the outer conductors (armor wire) to another piece of 
#16 copper wire. The leads from the Mecca plug were then soldered to 
the copper wires, and the splice was sealed using Scotch Fill, Scotch 
tape, and Scotch coat. For protection against mechanical damage, the 
splice was located in a small cutout about two inches from the end of 
the PVC pipe casing and under a steel guard that was secured by the 
last of the cable clamps. 

For the laying operation, the cable was mounted on a Standard 
Reelmaster HRD-3 cable trailer that was borrowed from the local 
telephone company. The trailer was secured close to the stern of the 
ship, obviating the need for a sheave for the laying operation. The 



mm 



-4- 



cable reel was braked by forcing 4 by 4 timbers against the reel flanges. 

Before lowering the instruments, 50-pound kedge anchors were 
secured to the cable with 20 feet of 1/2-inch polypropylene line so 
that they were just above the transducers. Cable clamps were used 
to keep the rope from sliding on the cable. The purpose of the anchors 
was to keep the transducers from being pulled along the rough ocean bottom 
during the cable-laying operation. 

When the ship was on location, the cable was run out a distance 
equal to the water depth. Measurement of this cable length was 
accomplished by counting turns of the cable spool. During the last 
part of the operation, the cable was frequently stopped and manually 
felt for bottom contact. On bottom contact, the ship then moved toward 
shore very slowly and cable was payed out at a rate slightly greater than 
the foreward speed of the vessel. When tension indicated that the 
anchors were holding, the ship's speed was increased to about 3 knots 
for the remainder of the run, and as the ship neared shore, small 
boats were used to pull a bight of cable to the beach and the cable was 
cut at the ship. 

Where the cables entered the water, they were protected by passing 
them through lengths of 1-1/2-inch PVC pipe which were joined by heavy 
rubber hoses. This added protection extended from the highest splash 
level to a point below the surf action. The pipe sections were secured 
firmly to rock on shore and to weights on the bottom to inhibit motion 
of the pipe during periods of heavy surf. 



ENVIRONMENT AND EXPOSURE 



The section of coast line where the installation is located is on the 
western or lee side of the island of Hawaii (Fig. 7). The bottom slopes 
off very rapidly from this coast making deep-water installations possible 
near shore (Fig. 8). Normally the sea is relatively calm and the 
weather clear, affording excellent working conditions. The 90-fathom 
gage was installed 2.2 nautical miles seaward from Keauhou Bay at the 
outer edge of a gradually sloping shelf of 40 fathoms mean depth. The 
transducer itself is just over the lip of a very steep drop of the ocean 
floor. The 288-fathom gage is 1.4 nautical miles from shore, near the 
Kona Airport. It too is on the slope of a very steep drop-off of the 
ocean bottom. The two transducers are 5 miles apart. Because the 
transducers are located on very steep slopes, the classical laws of 
pressure signal attenuation vs. depth for ocean swell are not directly 
applicable. 







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TRANSDUCER CALIBRATION 



The Vibrotron selected for the 90-fathom installation has an excep- 
tionally small temperature coefficient of 0.04 Hz per degree centigrade. 
The sensitivity of the Vibrotron is 4.63 cps/psi. Since this sensitivity 
is doubled in the mixer, the sensitivity at the 400-Hz output is 9.26 Hz/psi. 
Speaking in terms of water level, the sensitivity is 4.08 cps per foot of 
ocean-surface vertical movement, and a one-degree temperature change of 
the transducer would produce a signal change corresponding to about a 
quarter of an inch of ocean surface change. This excellent temperature 
stability makes the 90-fathom transducer useful as an offshore tide gage. 
The actual temperature variations at the gage location will be the subject 
of a future research project. 

The 288-fathom gage has a sensitivity of 8.074 Hz per psi and a rather 
poor temperature coefficient of 6.24 Hz per degree centigrade. The bees 
wax insulation, however, does prevent any environmental temperature varia- 
tion of tsunami period from reaching the transducer. Also, as the gage is 
at a greater depth, the environmental temperature changes are likely to 
be smaller. 

Under constant input pressure, both gages indicated an equivalent rms 
noise level of less than 1/32 inch of water during laboratory tests. For 
on-sight checking of the system, a one MHz multiple-period counter, a 
digital to analog converter, and a strip chart recorder were employed. 
Figures 9 and 10 show typical analog conversions of the signals from the 
transducers. 



CONCLUSION 



One of the design criteria for the instrument system was that it 
should be able to record the actual noise level of the ocean in the period 
range where this noise level is known to be very low (Munk e_t al . , 1963; 
Snodgrass e_t al. , 1966). The performance has met this criterion. 

The installation was designed to be semi -permanent. It is hoped that 
long-term records can be made from these gages which will, upon analysis, 
yield significant information on the nature of this noise level. 



-6- 



REFERENCES 



Munk, W. H., G. R. Miller, F. E. Snodgrass, and N. F. Barber, 1963, 
Directional recording of swell from distant storms, Roy. Soc . 
London Phil. Trans. A, 255, 505-584. 



Snodgrass, F. E., G. W. Groves, K. F. Hasselmann, G. R. Miller, W. H. 
Munk, and W. H. Powers, 1966, Propagation of ocean swell across 
the Pacific, Roy. Soc. London Phil. Trans. A , 259, 431-497. 

Vitousek, M. J., 1965, An Evaluation of the Vibrotron Pressure 

Transducer as a Mid-ocean Tsunami Gage, Hawaii Inst. Geophys . 
Report 65-13 , 12 pp., 7 figs. 



X 

o 

z 




ELAPSED TIME IN MINUTES 

Fig. 9. Typical record, 90-fathom gage (Keauhou) 



x 




15 20 25 30 

ELAPSED TIME IN MINUTES 



35 



40 



45 



Fig. 10. Typical record, 288-fathom gage (Kona Airport). 



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35 



Reprinted from TRANSACTIONS AMERICAN GEOPHYSICAL UNION Vol. 48, No. 2 



Reprinted from 

U. S. National Report, 1963-1967 

Fourteenth General Assembly 

Transactions, American Geophysical Union 

Vol. 48, No. 2, June 1967 



Tides and Other Long Period, Waves 
Bernard D. Zetler 

Institute for Oceanography 

U. S. Environmental Science Services Administration 

Silver Spring, Maryland 



Until recent years, the subject of tides rested 
comfortably on a plateau of achievement dat- 
ing back almost to the beginning of this cen- 
tury. Within the past few years, however, the 
electronic computer has suddenly transformed 
all aspects of the field: observations, reductions, 
analyses, predictions, and research. It is ironic, 
in a sense, that significant improvements in 
predicting techniques have been made in tides, 
the only phenomenon in physical oceanography 
for which there was a reasonably satisfactory 
level of achievement already. Some progress 
has been made in studies of tsunamis, but the 
major need, a real-time method of forecasting 
tsunami heights, has not yet been developed. 

Tide predictions. Munk and Cartwright 
[1966] developed a response method of predic- 
tion, in which the input functions are the time- 
variable spherical harmonics of the gravita- 
tional potential and of radiant flux on the 
Earth's surface. This method is the first suc- 
cessful major departure from the traditional 
solutions, in which the tide oscillations are de- 
scribed "by the amplitudes and phase lags for a 
finite set of cosine curves of predetermined fre- 
quencies. Previously, the only nongravitational 
constituents had been the first and second har- 
monics of the seasonal variations; the response 
method uses a radiational input in all species. 



The proposal to substitute the Munk-Cart- 
wright method for the traditional prediction 
procedure warrants careful consideration, fo r 
there is much more at stake than just the sta- 
tistical comparisons of residual variance [Zetler 
and Lennon, 1967]. If the new procedure is ac- 
cepted, the tidal harmonic constants will no 
longer be available. These constants are used 
not only for predictions but for co-tidal and 
co-range charts and tidal characteristics as 
well. The complex admittances obtained from 
the weights assigned to the various input series 
are proposed to replace these constants as a 
measure of response of the oceans to the tide- 
producing forces. If one plots the phase angles 
for the traditional semidiurnal harmonic con- 
stants as a function of frequency, one usually 
finds a siiarp bend or even a discontinuity at 
30° per solar hour. It is not reasonable that 
the oceans should exhibit so sharp a variation 
in response to a particular frequency. By way 
of contrast, the Munk-Cartwright admittances 
in species 2 are far smoother (undoubtedly 
related to the use of a radiational input), and 
even the jitter described in the paper has since 
been eliminated by adding third-order (largely 
frictional) interaction series to the input. The 
conclusion seems to be that the traditional S 2 
harmonic constants are a trigonometric com- 



592 



IUGG QUADRENNIAL REPORT (U.S.A.) 



bination of gravitational and radiational re- 
sponses of identical frequencies. If so, then in- 
ferences made for smaller constituents through 
equilibrium considerations only are incorrect. 
This appears to explain demonstrated inconsist- 
encies in the inference of some semidiurnal 
solar constituents. 

Thus, the Munk-Cartwright method offers 
not only the simplicity of a single set of input 
predictions that can be used in preparing pre- 
dictions for all places on the surface of the 
Earth but a more satisfactory documentation of 
the response of the oceans to the tide-produc- 
ing forces as well. Nevertheless, an argument 
against adopting this method is the rather ap- 
palling prospect, even in these days of electronic 
computers, of calculating the new type of re- 
sponses for much of the tidal data in the 
archives and of re-educating tidal authorities 
to think in terms of complex admittances rather 
than harmonic constants. It will be a difficult 
decision. 

Zetler and Cummings [in press, 1967] de- 
veloped a method for identifying and solving 
for the significant frequencies in the tide spec- 
trum. In working with shallow water tides at 
Anchorage, Alaska, they used a total of 114 
constituents in every species up to 12 cycles 
per day. Inasmuch as the Munk-Cartwright 
method can use any order of non-linear inter- 
action in the input functions, the method can be 
extended to shallow water tides, such as at 
Anchorage. This has not yet been done. 

Harris et al. [1965] described the program- 
ming effort that retired the U. S. Coast and 
Geodetic Survey mechanical tide predictor after 
more than fifty years of service. The change to 
electronic computers produced a saving in man- 
power and greater security, since the Coast 
and Geodetic Survey no longer has to rely on 
one unique piece of equipment. More important 
scientifically, however, the computer permits 
greater flexibility in predictions by removing 
the restriction of the 37 specific constituent 
speeds on the tide predicting machine. 

Tide observations and analysis. Barbee 
[1967] described three new tide gages: a digital- 
recording device driven by a float in the stand- 
ard stilling well, a pressure-sensing instrument 
suitable for installation in harsh environments 
or where no coastal structures exist, and a pres- 
sure-sensing gage capable of operating at great 



depth [also see Goodheart et al., 1965]. The 
Coast and Geodetic Survey uses the digital 
(one-tenth hour) data in a computer program 
that outputs times and heights of high and 
low waters, mean ranges, lunitidal intervals, 
various mean planes, and monthly extremes. 
Snodgrass [1967] developed a free falling in- 
strument capsule with a Vibroton absolute- 
pressure transducer for measuring pressure at 
a depth of several kilometers with very high 
resolution. 

Hicks et al. [1965] described tide observa- 
tions about 130 km offshore on the Atlantic 
continental shelf at about 210 and 260 meters. 
Alldredge and Fitz [1964] described observa- 
tions at 30 meters on a submerged stabilized 
platform in 1280 meters of water. Munk was 
named chairman of an international working 
group on deep sea tides at the 1965 IAPO meet- 
ing in Paris. 

Harris et al. [1963] programmed a least- 
square analysis that solves for the harmonic 
constants of all constituents simultaneously, as 
opposed to the traditional method of a modified 
Fourier analysis for individual constituents. 
After an objective evaluation of five analytical 
processes was completed [Zetler and Lennon, 
1967], the method was accepted by the Coast 
and Geodetic Survey for series of at least one 
year. Twenty-nine day analyses are still done by 
traditional formulas on a computer. Munk and 
Hasselmann [1964], in a study of super-resolu- 
tion, pointed out that the precision of tide pre- 
diction is ultimately limited by the underlying 
noise spectrum. Zetler et al. [1965] extended the 
least-square analysis approach to data observed 
in random time. 

Supported by an IUGG resolution at Berk- 
eley in 1963, Munk has collected, edited, and 
prepared (in computer-compatible format) long 
series of tide data for numerous places through- 
out the world. One method of tide data editing 
used at IGPP of the University of California 
at San Diego was described by Zetler and 
Groves [1964]. 

The U. S. Naval Oceanographic Office [1965] 
published a very useful atlas of tides and cur- 
rents in the North Atlantic. The engineering 
and legal aspects of tidal datum planes were de- 
scribed in considerable detail by Shalowitz 
[1962, 1964]. 

Studies of the continuum. Munk and Bull- 



ASSOCIATION OF PHYSICAL OCEANOGRAPHY 



593 



ard [1963] used narrow bandpass filters to ex- 
amine the level of the continuum between spe- 
cies (cycles per day). Munk et al. [1965] then 
extended the study by looking at the level be- 
tween the groups and even between the con- 
stituents within the same group. In the vicinity 
of strong tidal lines, they found that the con- 
tinuum rises into cusps, presumably because of 
nonlinear interaction of the lines with the peak 
of the continuum near zero frequency. The 
shallow water predictions by Zetle'r and Cum- 
mings [1967] indicated that nonlinear inter- 
actions of tidal lines probably contribute to 
the cusps; it has also been suggested that the 
cusps are associated with a modulation of the 
internal tides by the slowly varying thermal 
structure. Groves and Zetler [1964} used 50 
years of tide observations at San Francisco and 
Honolulu to find a reasonably uniform phase lag 
of maximum coherence over a wide range in the 
low frequencies, but they failed to find any sig- 
nificant peaks at frequencies other than those in 
tidal theory. Wunsch [1966] found that the 
biweekly and monthly tides are not purely 
equilibrium tides but forced planetary waves 
with a scale of the order of 1000 miles, much 
smaller than that of the tide-producing poten- 
tial or even of the oceans. Rattray and Charnell 
[1966] obtained planetary wave solutions for 
quasi-geostrophic free oscillations in enclosed 
basins of dimensions comparable to the Pacific, 
Atlantic, and Indian oceans. The baroclinic 
oscillations (restricted to regions adjacent to 
the equator or the ocean boundaries) may ex- 
plain observed fluctuations with periods of one 
or a few months; the barotropic oscillations 
that fill the complete basins may explain ob- 
served periods of three or more days. 

Sea level. Donn et al. [1964] prepared a 
very comprehensive survey of recent sea level 
studies. They included wind waves as well as 
long waves, pointing out that all sea waves are 
sea level variations. The complete range of 
wavelengths (centimeters to global) and wave 
periods (less than a minute to more than a 
century) was presented by Stommel [1963] in 
a schematic three-dimensional power spectrum 
of sea level variations. Inasmuch as wind waves 
are covered in a parallel report, sea level is used 
here in a smoothed sense, averaged over a pe- 
riod of a month or more. Patullo [1963] de- 
scribed seasonal variations on a regional basis 



and discussed the relative contributions of as- 
sociated phenomena. Rodeh [1966] cross-cor- 
related monthly means of sea level, atmospheric 
pressure, and sea temperature in a comprehen- 
sive study of sea level variations in the Pacific. 
Hicks and Shofnos [1965a] contoured the rate 
of land emergence in southeast Alaska from 
sea level observations and they [Hicks and 
Shofnos, 19656] made new determinations of 
regional sea level trends in the United States. 

Tidal energy. Miller [1966] has used recent 
tide and tidal current analyses to arrive at 
modified estimates for frictional dissipation of 
tidal energy. His estimate for the Bering Sea 
is considerably lower than previous estimates 
by Jeffreys and Heiskanen, but his total is com- 
parable. 

Tsunami. The tsunami generated by the 
Alaskan earthquake on March 28, 1964, de- 
vastated many coastal zones in Alaska and in- 
flicted severe damage on the west coast of the 
United States [Spaeth and Berkman, 1965]. 
The wave at Crescent City, California, reached 
21 feet above chart datum; this record eleva- 
tion was clearly related to the orientation of 
energy at the source. The Crescent City in- 
undations changed some opinions as to the 
vulnerability of the west coast of the United 
States to tsunamis of distant origin. 

Van Dorn [1964a] interpreted the available 
evidence to indicate a dipolar movement of the 
Earth's crust, centered along a line running 
from Hinchinbrook Island, Prince William 
Sound, southwesterly to the Trinity Islands. 
The U. S. Coast and Geodetic Survey [1964] 
listed the amount of vertical land movement at 
various places, the largest movement being a 
change of 31.5 feet on Montague Island. Donn 
[1964] suggested that the waves of up to 6 
feet that occurred at about the same time along 
the coasts of Louisiana and Texas were gen- 
erated by the seismic waves. 

The International Union of Geodesy and 
Geophysics [1964] issued a comprehensive bib- 
liography of tsunamis compiled and edited by 
the U. S. Coast and Geodetic Survey. Berning- 
hausen [1964, 1966] has compiled data on 
tsunamis in the Atlantic and Indian oceans. 
Weigel's [1964] Oceanographic Engineering, 
and Wilson's [1965] report are fine references 
for many aspects of tsunami research. Miller 
[1964] and Loomis [1966] showed that spectra 



594 



IUGG QUADRENNIAL REPORT (U.SA.) 



for various tsunamis at any one recording sta- 
tion are similar in appearance, whereas spectra 
for the same tsunami at different recording sta- 
tions are ordinarily quite different. Van Dorn 
[19646] demonstrated that the theory of geo- 
metric optics adequately predicts the behavior 
of waves radiating from a large explosion. 
Wong et al. [1964] used linearized shallow wa- 
ter wave theory in analyzing the interaction of 
a tsunami with an isolated oceanic island. 

Tsunami warning systems. The U. S. Coast 
and Geodetic Survey [1965] was host to the 
Intergovernmental Oceanographic Commission 
Conference on the International Aspects of the 
Tsunami Warning System at Honolulu in 1965. 
The twelve countries represented at the meeting 
discussed possible improvement in the existing 
warning systems and made a series of recom- 
mendations to the Intergovernmental Oceano- 
graphic Commission. A local tsunami warning 
service was developed for Alaska, centered at 
Anchorage. The Hilo model tests were com- 
pleted by the U. S. Army Corps of Engineers; 
the results were summarized in a report of the 
Hilo Technical Tsunami Advisory Council 
[1965]. A report by Cox [1964] described the 
state of the art in tsunami forecasting. Vitousek 
[1965] continued his efforts to develop a mid- 
ocean tsunami gage, a development that was 
urgently needed not only to improve the warn- 
ing service but for research purposes as well. 

Joint tsunami research effort. The U. S. 
Coast and Geodetic Survey and the Institute of 
Geophysics, University of Hawaii, established 
the Joint Tsunami Research Effort on the 
campus of the University. Under a subsequent 
reorganization, the Environmental Science Serv- 
ices Administration took responsibility for the 
government participation. Several very capable 
scientists have joined the ESSA and University 
of Hawaii contingents, and some promising re- 
search studies are now under way. 

References 

Alldredge, L. R., and J. C. Fitz, Submerged 
stabilized platform, Deep-Sea Res., 11, 935-942, 
1964. 

Barbee, W. D., Tide gages in the U. S. Coast and 
Geodetic Survey, Report, Unesco and IAPO 
Symp. Tide Gage Instrumentation, Paris, 1965, 
in press, 1967. 

Berninghausen, W. H., Tsunamis and seismic 
seiches reported from the eastern Atlantic 



south of the Bay of Biscay, Bull. Seismolopical 
Soc. Am., 64, 439-142, 1964. 

Berninghausen, W. H., Tsunamis and seismic 
seiches reported from regions adjacent to the 
Indian Ocean, Bull. Seismological Soc. Am., 66, 
69-74, 1966. 

Cox, D. C, Tsunami forecasting, Hawaii Inst. 
Geophys., Univ. Hawaii, H1G-64-15, 22 pp., 1964. 

Donn, W. L., Alaskan earthquake of 27 March 
1964 : Remote seiche stimulation, Science, 145, 
261, 1964. 

Donn, W. L., J. G. Pattullo, and D. M. Shaw, Sea- 
level fluctuations and long waves, in Research 
in Geophysics, II, Solid Earth and Interface 
Phenomena, pp. 243-267, Massachusetts Insti- 
tute of Technology Press, Cambridge, Mass., 
1964. 

Goodheart, A. J., C. W. Iseley, and S. D. Hicks, 
Deep sea tide gage, in Ocean Science and Ocean 
Engineering, vol. 1, Marine Technology Society 
and American Society of Limnology and Ocea- 
nography, 1965. 

Groves, G. W., and B. D. Zetler, The cross spec- 
trum of sea level at San Francisco and Hono- 
lulu, J. Marine Res., 22, 269-275, 1964. 

Harris, D. L., N. A. Pore, and R. Cummings, The 
application of high speed computers to practi- 
cal tidal problems, Abstracts of Papers, VI, 
IAPO, XIII General Assembly, IUGG, Berke- 
ley, 1963. 

Harris, D. L., N. A. Pore, and R. A. Cummings, 
Tide and tidal current prediction by high 
speed digital computer, Intern. Hydrographic 
Rev., 42, 95-103, 1965. 

Hicks, S. D., A. J. Goodheart, and C. W. Iseley, 
Observations of the tide on the Atlantic con- 
tinental shelf. J. Geophys. Res., 70, 1827-1830, 
1965. 

Hicks, S. D., and W. Shofnos, Yearly sea level 
variations for the United States, J. Hydraulics 
Div., Proc. Am. Soc. Civil Engrs., HY 5, 23-32, 
1965a. 

Hicks, S. D., and W. Shofnos, The determination 
of land emergence from sea level observations 
in southeast Alaska, J. Geophys. Res., 70, 3315- 
3320, 1965b. 

Hilo Technical Tsunami Advisory Council, Physi- 
cally feasible means for protecting Hilo from 
tsunamis (unpublished), Third Report to the 
Board of Supervisors, Hawaii County, through 
Its Tsunami Advisory Committee, 38 pp., 1965. 

International Union of Geodesy and Geophysics, 
Annotated bibliography on tsunamis, Mono- 
graph 27, 249 pp., 1964. 

Loomis, H. G., Spectral analysis of tsunami rec- 
ords from stations in the Hawaiian Islands, 
Bull. Seismological Soc. Am., 56, 697-713, 1966. 

Miller, G. R., Tsunamis and tides, PhX). disserta- 
tion, University of California, San Diego, 1964. 

Miller, G. R., The flux of tidal energy out of deep 
oceans, J. Geophys. Res., 71, 2485-2490, 1966. 

Munk, W. H., and E. C. Bullard, Patching the 
long- wave spectrum across the tides, J. Geophys. 
Res., 68, 3627-3634, 1963. 



ASSOCIATION OF PHYSICAL OCEANOGRAPHY 



595 



Munk, W. H., and D. E. Cartwright, Tidal spec- 
troscopy and prediction, Phil. Trans. Roy. Soc. 
London, A, 259, 533-581, 1966. 

Munk, W., and K. Hasselmann, Super-resolution 
of tides, in Studies on Oceanography (Hidaka 
Volume), pp. 339-344, University of Washington 
press, Seattle, Washington, 1964. 

Munk, W. H, B. Zetler, and G. W. Groves, 
Tidal cusps, Geophys. J., #), 211-219, 1965. 

Patullo, J. G., Seasonal changes in sea level, in 
The Sea, vol. 2, edited by M. N. Hill, pp. 485- 
496, Interscience, New York and London, 1963. 

Rattray, M., Jr., and R. L. Charnell, Quasi- 
geostrophic free oscillations in enclosed basins, 
J. Marine Res., 24, 82-103, 1966. 

Roden, G. I., Low-frequency sea level oscillations 
along the Pacific coast of North America, J. 
Geophys. Res., 71, 4755-4776, 1966. 

Shalowitz, A. L., Shore and sea boundaries, U. S. 
Coast Geodetic Surv. Publ. 10-1, vol. 1, 420 pp., 
1962. 

Shalowitz, A. L., Shore and sea boundaries, U. S. 
Coast Geodetic Surv. Publ. 10-1, vol. 2, 749 pp., 
1964. 

Snodgrass, F. E., Digital recording of tides in the 
deep sea, Report, Unescb and IAPO Symp. Tide 
Gage Instrumentation, Paris, 1965, in press, 1967. 

Spaeth, M. G., and S. C. Berkman, The tsunami 
of March 28, 1964, as recorded at tide stations 
(unpublished), 59 pp., U. S. Coast and Geodetic 
Survey, 1965. 

Stommel, H., Varieties of oceanographic experi- 
ence, Science, 139, 572-576, 1963. 

U. S. Coast and Geodetic Survey, Preliminary re- 
port, tide datum plane changes, Prince William 
Sound, Alaskan earthquake, March-April 1964 
(unpublished), 4 pp., 1964. 

U. S. Coast and Geodetic Survey, Intergovern- 
mental Oceanographic Commission report of 
the working group meeting on the international 
aspects of the tsunami warning system in the 
Pacific, Honolulu, Hawaii, April 27-30, 1965 
(unpublished), 33 pp., 1965. 



U. S. Naval Oceanographic Office, Oceanographic 
atlas of the North Atlantic Ocean, sect. 1, Tides 
and currents, Publ. 700, 1965. 

Van Dorn, Wm. G., Source mechanism of the 
tsunami of March 28, 1964, in Alaska, Proc. 
Ninth Conf. Coastal Eng., Am. Soc. Civil Engrs., 
10, 166-190, 1964a. 

Van Dorn, Wm. G., Explosion-generated waves in 
water of variable depth, J. Marine Res., 22, 123- 
138, 1964b. 

Vitousek, M. J., An evaluation of the vibroton 
pressure transducer as a mid-ocean tsunami 
gage, Hawaii Inst. Geophys., Univ. Hawaii, 65- 
13, 12 pp., 1965. 

Wiegel, R. L., Oceanographical Engineering, 532 
pp., Prentice-Hall, Jnc, Englewood Cliffs, New 
Jersey, 1964. 

Wilson, B. W., Generation and dispersion char- 
acteristics of tsunamis, in Studies on Oceanog- 
raphy (Hidaka Volume), pp. 413-444, Univer- 
sity of Washington Press, Seattle, Washington, 
1965. 

Wong, K. K., A. T. Ippen, and D. R. F. Harleman, 
On the interaction of a tsunami with an isolated 
oceanic island, Trans. Am. Geophys. Union, 45, 
69-70, 1964. 

Wunsch, C. I., On the scale of the long-period 
tides, Ph.D. dissertation, Massachusetts Insti- 
tute of Technology, 1966. 

Zetler, B. D., and R. A. Cummings, A harmonic 
method for predicting shallow water tides, J. 
Marine Res., 25, 103-114, 1967. 

Zetler, B. D., and G. W. Groves, A program for 
detecting and correcting errors in long series of 
tidal heights, Intern. Hydrographic Rev., 41, 
103-107, 1964. 

Zetler, B. D., and G. W. Lennon, Some compara- 
tive tests of tidal analytical processes, Intern. 
Hydrographic Rev., 44, 139-147, 1967. 

Zetler, B. D., M. D. Schuldt, R. W. Whipple, and 
S. D. Hicks, Harmonic analysis of tides from 
data randomly spaced in time, /. Geophys. Res., 
70, 2805-2811, 1965. 



36 



Reprinted from INTERNATIONAL HYDROGRAPHIC REVIEW Vol. kk , No. 1 

SOME COMPARATIVE TESTS 
OF TIDAL ANALYTICAL PROCESSES 

by B. D. Zetler 
Physical Oceanography Laboratory, Institute for Oceanography, ESSA 

and G.W. Lennon 
University of Liverpool Tidal Institute and Observatory 



Abstract 



Tests have been conducted on five analytical processes and the results 
have been examined by statistical and power spectral techniques. Tide 
observations at Atlantic City (small range and large low-frequency noise), 
Swansea (large range and noise primarily in tidal frequencies), and San 
Francisco (small range and moderate low frequency noise) were used in the 
study. Residuals were obtained by subtracting the predicted hourly heights 
from observations and were evaluated for total energy (variance) and energy 
per frequency band. The latter calculation was found to be useful in compar- 
ing residual energy for particular portions of the frequency spectrum. 



Introduction 

The advent of electronic computers has made possible new approaches 
to tidal analysis. Numerous organizations have initiated least squares ana- 
lytical approaches in which a set of fixed frequencies (speeds of tidal 
constituents) is proposed to fit the data so that the sum of the squares of 
the residuals is a minimum. This modified the traditional approach, as 
exemplified by Doodson (1928) and Schureman (1941), in which only one 
constituent is examined at a time and the results are modified for the inter- 
ference effects of other constituents in the same species. Munk and 
Gartwright (1966) have recently developed a response method of prediction 
in which the input functions are the time-variable spherical harmonics of 
the gravitational potential and of radiant flux on the Earth's surface. 

This study was initiated to permit comparative evaluations of some of 
the proposed analytical processes. Inasmuch as Munk and Hasslemann 
(1964) have shown that the ability to separate two frequencies depends on 
the noise level, it was decided to conduct the tests with real data. The tests 
have been conducted on the Coast and Geodetic Survey method (Schureman, 
1941), the Harris-Pore-Cummings (1963) least squares method that has 



140 INTERNATIONAL HYDROGRAPHIC REVIEW 

been accepted by the Coast and Geodetic Survey for series of one year, the 
Doodson method as treated by Lennon (1965), the Murray (1963) least 
squares method, and the Munk-Cartwright (1966) method. The data, 
hourly heights of tide, included Atlantic City (1939), Swansea (1961-1962), 
and San Francisco (1931 and 1939). 



Atlantic City Comparisons 

This is the only test in the study that involves all five methods. Table 1 
shows the results obtained by analyzing the data, predicting for the same 
period by using the derived constants, subtracting the predictions from the 
observations, and examining the residuals. At first, only the total variance 
of the residuals was obtained, but it quickly became obvious that a more 
refined procedure was needed because the small differences between total 
variances appeared relatively insignificant. Therefore, the power spectra 
were calculated to permit comparisons of residual energy at various fre- 
quencies. A peak of energy in the low frequencies shows up clearly on 
figure 1 (the spectrum of residuals from the Doodson method), even though 



10' 



10" 



SPECTRAL ANALYSIS OF ATLANTIC CITY RESIDUALS 
DOODSON ANALYSIS 




1 2 3 4 5 6 7 8 9 10 11 12 

Frequency in cpd 

Fig. 1. — Spectrum of residuals from Doodson method for Atlantic City, 1939. 



the energy scale (vertical) is logarithmic. Atlantic City is directly on the 
open coast and the shallow water fetch is short. Hence, the non-linear 
interaction terms (ordinarily manifested as compound tides in the high 
frequencies) are small. However, the station is wide open to the effect of 
all storms on the North Atlantic and the results confirm that the noise is 
due to storms having effective periods of greater than a day. Figure 2 shows 
the large daily fluctuations in mean sea level for the year analyzed. 



COMPARATIVE TESTS OF TIDAL ANALYSES 



141 



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142 INTERNATIONAL HYDROGRAPHIC REVIEW 

The degree of resolution in the power spectrum analysis was chosen 
to adequately separate the species, to minimize the computer effort, and to 
have sufficient degrees of freedom to provide reasonable confidence in the 
results. Inasmuch as the data are hourly, the Nyquist frequency is 12 
cycles per day. Using 100 lags in the autocorrelations, we get a " delta f " 
of .12 cpd which essentially separates the species by about eight values, 
a satisfactory separation. The number of degrees of freedom in a Tukey 
analysis is roughly 2 N/M, where N is the number of data points and M 
is the number of lags used in the autocorrelations (Munk et ah, 1959). With 
a year of data, there are about 170 degrees of freedom, a rather conservative 
and satisfactory number. 

The results shown in table 1 show the Munk-Cartwright method to 
have a small advantage over the two least square methods. The small 
differences between the Murray and Harris-Pore-Cummings methods may 
be caused by other factors, such as the number of significant digits used in 
the calculation. Both least squares methods appear to do slightly better 
than the Doodson method. Considering the limitations on accuracy imposed 
by the minimizing of correction processes when hand computations were 
the order of the day, the Doodson method does remarkably well. The fact 
that the Harris-Pore-Cummings does as well as the Murray with 19 fewer 
constituents relates to the particular station being analyzed, the additional 
constituents (primarily compound tides) are essentially trivial (all are less 
than .02 foot) and therefore do not give the Murray (or Doodson) method 
any significant advantage for this particular station. The Harris-Pore- 
Cummings computer program is dimensioned for 41 constituents and this 
was considered a limiting characteristic at the time the computations in 
this study were made. Since that time the program has been used with as 
many as 114 constituents for Anchorage (Zetler and Cummings, 1966) 
simply by separating the constituents into groups and using the restriction 
that all constituents within any species had to be included in the same 
group. As a matter of fact, this approach reduces the computing effort. For 
example, it is far simpler to reduce three 40 x 40 matrices than one 120 
x 120 matrix. The poorer results for the traditional C&GS method are 
clearly related to the small number of constituents in the solution and 
there is no doubt that it would have moved into the general area of the 
other results had a greater effort been considered warranted. The C&GS 
harmonic constants for Atlantic City were taken from the archives and 
were typical of the methods that were used twenty years ago when manual 
stencil summation for each constituent limited strongly the number of 
constituents sought. In more recent years, summations have been made 
on an electronic computer but the remainder of the process is continued 
by hand (Schureman, 1941). There is no question that the remainder of the 
process can be programmed for an electronic computer and it has recently 
been done for 15- and 29- day series. It has not been programmed for 
a year by the Coast and Geodetic Survey because the least square approach 
has been shown to be acceptable and to have greater flexibility in the choice 
of series length and by virtue of not necessarily requiring data equally 
spaced in time (Zetler et al., 1965). 

Consideration was given to plotting in one illustration the spectra for 



COMPARATIVE TESTS OF TIDAL ANALYSES 



143 



all five sets of residuals. In general they are so close together that the 
composite graph would be confusing. Therefore only one is shown in 
figure 1 to more or less typify the station characteristics. 



Swansea Comparisons 

Although the test conditions for the Swansea data were comparable 
to those for Atlantic City, it is clear that the results in table 1 cannot be 
interpreted in terms of comparative evaluations of the Harris-Pore- 
Cummings and Doodson methods. Unlike the conclusions for Atlantic City, 
it is obvious that some of 23 additional constituents (60 compared to 37) 
improve the prediction and thereby reduce the residual variance. 

In species 2 (two cycles per day) there are six constituents in the 
Doodson analysis that are not included in the standard Coast and Geodetic 
Survey analysis. The total energy in these six (using energy equals one 
half amplitude squared) is .0256, somewhat greater than the .0173 difference 
obtained from the table 1 values for residual variance in species 2. Inasmuch 
as the calculated values for one constituent can change if another consti- 
tuent in the same species is added to the model in the least square analysis, 
no rigorous comparisons can be made from the results. On the other hand, 
it seems obvious that if the same model (set of constituents) were used with 
both methods, it is unlikely the results would differ significantly. Therefore 
the principal interest in these results is in Figure 3 where the contribution 
of the additional constituents is demonstrated in the various species. Even 
here, in considering these comparisons, it is important to keep in mind 
that the vertical scale is logarithmic. 



10' 



10- 4 



SPECTRAL ANALYSIS OF SWANSEA RESIDUALS 




\ * HARRIS-PORE-CUMMINGS 



DOODSON 



Fig. 3. 



5 6 7 

Frequency in cpd 



10 



12 



Spectra of residuals from Doodson and Harris-Pore-Cummings methods 
for Swansea, one year (1961-1962). 



144 



INTERNATIONAL HYDROGRAPHIC REVIEW 



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COMPARATIVE TESTS OF TIDAL ANALYSES 



145 



San Francisco Comparisons 

The results shown in table 1 for the Coast and Geodetic Survey and 
the Munk-Cartwright methods for San Francisco are derived from different 
basic data and therefore they are not directly comparable. Nevertheless, 
some of the results are quite interesting. 

The C&GS predictions for San Francisco for both 1931 and 1939 are 
based on mean harmonic constants from 11 one-year analyses and the 
annual and semi-annual constituents (Sa and Ssa) are based on 19 years 
of monthly mean sea level. The 1931 Munk-Cartwright predictions were 
based on an analysis of the same year and therefore it was to be expected 
that the residual variance would be less. Spectra were not computed for 
the 1931 residuals. 

The 1939 Munk-Cartwright predictions were made with weights 

derived from just one year, 1931. Table 1 shows the C&GS ahead on total 

variance but behind in species 2. Figure 4 shows comparisons in each 
species. 

The big difference is in the low frequency portion of the spectrum. 
Although Sa and Ssa fall within the first frequency band (0 to .06 cpd), one 
effect of tapering the autocorrelations is to widen the main pass band to 
include the two bands on either side, in this case to to .30 cpd (Munk 
et al., 1959). Inasmuch as Sa and Ssa are due to thermal variations (the 
astronomical input to Ssa is small), they are only quasi-stationary and a 
mean of 19 years of data can be expected to furnish a more reliable 
predictor than just one year. Therefore, it is not surprising to find the sum 



10' 



10 l 



SPECTRAL ANALYSIS OF SAN FRANCISCO RESIDUALS 




5 6 7 

Frequency in cpd 



10 



12 



Fig. 4. — Spectra of residuals from Munk-Cartwright and Coast and Geodetic Survey 

methods for San Francisco, 1939. 



146 INTERNATIONAL HYDROGRAPHIC REVIEW 

of residual energy from to .30 cpd is .0898 for the Munk-Cartwright 
method and .0683 for the C&GS method. 

The Munk-Cartwright method does remarkably well with stationary 
phenomena in species 1, 2, and 3. Part of its apparent advantage is tempered 
by the smaller number of variables in the C&GS method (2 x 18 = 36 
compared to 59) but nevertheless it is quite an achievement to do so much 
better with the one year of input compared to 11 years for the C&GS 
method. 

The C&GS method appears to have done better in species 4 but actually 
there was no contest. The Munk-Cartwright prediction did not include an 
input for bilinear interaction of species 2 with itself which would have 
produced a species 4 prediction. A bilinear input for the interaction of 
species 1 with species 3 could have been used also but this would have 
been considerably less important. 



Summary 

Objective test procedures have been developed for comparing tidal 
analytical processes. The use of power spectral techniques for evaluating 
residual energy for particular species has been found to be a useful tool. 
As a direct result of these tests, the Coast and Geodetic Survey has accepted 
the Harris-Pore-Cummings least squares procedure for the routine analysis 
of series of one year in length. 

In retrospect, it is unfortunate that the only direct comparison of the 
five analytic methods was done with the least complicated set of data. This 
deprives the more sophisticated methods of a chance to demonstrate 
competence to cope with additional complications. Perhaps the study can 
be extended in the future to include various methods for predicting shallow 
water tides. 

During the tests, it was found that the residual variances from the 
Harris-Pore-Cummings method did not match the claimed reduction in 
variance computed as part of the program. The resulting investigation 
found a small error in the program and this was corrected. The data shown 
in this paper are from the corrected program and therefore some values do 
not match the data in a preliminary report (Zetler and Lennon, 1966). The 
detection of the discrepancy was an unanticipated by-product of the study. 

An initial objective of this study was to compare computer cost as 
well as accuracy of analysis. This becomes confusing for various reasons, 
particularly since the same computers at different installations may have 
significantly different costs. With one exception, the Munk-Cartwright 
method, the computer costs are so low that differences are not very signi- 
ficant. Unlike the other methods which were developed for routine produc- 
tion usage, the Munk-Cartwright method was devised for research purposes. 
It would be unfair to compare it on the basis of cost until some effort has 
been made to make the program more efficient in a cost sense. 

Possibly the greatest importance of the study is that representatives of 
tidal offices in two countries have agreed to use the same data to evaluate 
their analytical processes and have proposed criteria for the comparisons. 



COMPARATIVE TESTS OF TIDAL ANALYSES 147 

The authors hope that this is the beginning of a broader international 
program along similar lines. 

Acknowledgement 

The authors thank Dr. Walter Munk for providing the training and 
computing facilities necessary for the tests involving the Munk-Cartwright 
response method. The availability of BOMM (Bullard et al., 1966), a 
system of programs for the analysis of time series, reduced significantly the 
programming effort in this study. 



REFERENCES 

Bullard, E.G., Oglebay, F. E., Munk, W. H. and Miller, G. B. (1966) : 
A User's Guide to BOMM, Institute of Geophysics and Planetary 
Physics, University of California, San Diego. 

Doodson, A. T. (1928) : The Analysis of Tidal Observations, Phil. Trans, 
of the Royal Society of London, Series A, Vol. 227. 

Harris, D. Lee, Pore, N. A. and Cummings, Bobert (1963) : The Application 
of High Speed Computers to Practical Tidal Problems, Abstracts of 
Papers, Vol. VI, IAPO, XIII General Assembly, IUGG, Berkeley, 
VI-16. 

Lennon, G. W. (1965) : The Treatment of Hourly Elevations of the Tide 
using an IBM 1620, International Hydrographic Review, Vol. XLII, No. 
2, 125-148. 

Munk, W. H. and Cartwright, D. E., in press, Tidal Spectroscopy and 
Prediction, Royal Society Transactions A. 

Munk, W. H. and Hasselmann, K. F. (1964) : Super-Resolution of Tides, 
Studies on Oceanography (Hidaka Volume), 339-344. 

Munk, W. H., Snodgrass, F. E. and Tucker, M.J. (1959) : Spectra of Low- 
Frequency Ocean Waves, Bull, of the Scripps Institution of Oceano- 
graphy, Vol. 7, No. 4, 283-362, University of California Press. 

Murray, M. T. (1963) : Tidal Analysis with an Electronic Digital Computer, 
Cahiers Oceanog., 699-711. 

Schureman, Paul (1941) : Manual of Harmonic Analysis and Prediction 
of Tides, U.S. Coast and Geodetic Survey Spec. Pub. No. 98. 

Zetler, B. D. and Cummings, B. A. (1966) : An Objective Method for Identify- 
ing Hidden Frequencies in Shallow Water Tides, Abstract in Transac- 
tions, American Geophysical Union, Vol. 47, No. 1, 117-118. 

Zetler, B. D. and Lennon, G. W, in press, Evaluation Tests of Tidal 
Analytical Processes, UNESCO Publication on Tide Symposium at 
Paris, 1965. 

Zetler, B. D., Schuldt, M. D., Whipple, B. W. and Hicks, S. D. (1965) : 
Harmonic Analysis of Tides from Data Bandomly Spaced in Time, 
Journal of Geophysical Research, Vol. 70, No. 12, 2805-2811. 



37 



Reprinted from PROCEEDINGS THE ELEVENTH PACIFIC SCIENCE CONGRESS 
Volume 2, Oceanography , Toyko 1966 



A HARMONIC METHOD OF PREDICTING SHALLOW WATER TIDES 

Bernard D. Zetler* and Robert A. Cummings **. * Institute for Oceanography, Environmen- 
tal Science Services Administration. ** Coast and Geodetic Survey, Environmental 
Science Services Administration 

The development of an objective technique for identifying significant hidden 
frequencies in the spectrum makes it possible to accurately predict shallow water 
tides by harmonic methods. For Anchorage, Alaska, the 114 constituents that are used 
include frequencies in every species (cycles per day) from to 12. This large set 
of constituents improves the predictions (times of high and low waters, range of tide, 
and shape of curve). The technique was also applied to Philadelphia data. Two addi- 
tional years at Philadelphia were then analyzed for the same constituents. The com- 
parison of harmonic constants for the three years permits an evaluation of the station- 
ary characteristics of the added constituents. 



38 



Reprinted from JOURNAL OF MARINE RESEARCH Vol. 25, No. 1 

A Harmonic Method 

for Predicting Shallow-water Tides 

Bernard D. Zetler and Robert A. Cummings 

Physical Oceanography Laboratory 
Institute for Oceanography, ESS A 
Division of Oceanography 
U.S. Coast and Geodetic Survey, ESS A 

ABSTRACT 

The development of an objective technique for identifying significant hidden frequencies 
in the spectrum makes it possible to accurately predict shallow-water tides by harmonic 
methods. For Anchorage, Alaska, the 114 constituents used include frequencies in every 
species (cycles per day) from o to 12. The larger set of constituents improved the predictions 
in times of high and low waters, range of tide, and shape of curve. The stationary character- 
istics of some of the added constituents have been tested with three years of Philadelphia data. 

This study was initially designed for a specific purpose — to improve tidal 
predictions at Anchorage, Alaska. Anchorage is located at the northern end 
of Cook Inlet near the western end of the Gulf of Alaska. The mean range 
of tide at Anchorage is about 25 feet. After oil was found in the area, huge 
deep-draft tankers required more accurate tidal predictions than were available 
by using the standard U.S. Coast and Geodetic Survey procedures for tidal 
analysis and prediction (9). 

There was no question as to why the problem existed. Those harmonic 
constants that were determined in the Coast and Geodetic Survey analysis 
showed large amplitudes for some shallow-water constituents — clear indic- 
ations of additional significant compound tides that are not included in the 
routine analysis. The compound tides are associated with the distortion of the 
sinusoidal shape of the tidal curve as the tidal wave travels over shallow depths (5). 

British authorities have had to cope with shallow-water tides to a much 
greater extent than the U.S. Coast and Geodetic Survey, and therefore they 
have traditionally used 60 tidal constituents (3) compared with the 37 used 
by the Coast and Geodetic Survey. In some extreme cases, the 60 constituents 
do not adequately describe the shape of the curve, and the British have devel- 
oped a non harmonic modification of their procedures to cope with these tides (4). 

1. Accepted for publication and submitted to press 15 October 1966. 

IO3 

REPRINT FROM JOURNAL OF MARINE RESEARCH, VOLUME 25, 1, 1967 



104 ^Journal of Marine Research [25,1 

A logical approach, therefore, was to send the Anchorage data to the Tidal 
Institute and Observatory, University of Liverpool, for analysis and prediction 
until such time as the Coast and Geodetic Survey could learn the British 
techniques. However, this did not solve the problem. We were informed that 
the Tidal Institute routine analysis obviously would not match the shape of 
the curve and that a continuous record of hourly heights for one year would 
be required for the nonharmonic method. Inasmuch as the harbor at Anchor- 
age freezes every winter, the required length of record was not available. 
Although an effort to get a continuous year of record was initiated by installing 
a pressure gauge on the bottom, there remained an element of doubt as to 
whether the tidal characteristics remain unchanged during the winter freeze. 

Fortunately, recent technical changes in tidal analysis and prediction made 
possible another approach. Essentially, the principal change provided greater 
flexibility in both analysis and prediction in that additional constitutents can 
now be included. Until now there was a constraint to work only with a fixed 
set of constituents; no others could be readily analyzed for, nor could they be 
included in, the prediction. 

Traditional analysis included (i) a modified Fourier analysis for particular 
frequencies, (ii) a modification of the results for the interference effects of 
nearby frequencies, and (iii) an elimination of sideband contributions of fre- 
quencies in the same species — the same number of cycles per day (9,3). A least- 
square analysis in which any combination of frequencies is inserted as a model 
is now readily accomplished on a computer. A recent study showed that the 
harmonic constants for the same set of constituents are slightly more accurate 
than those obtained by the previous Coast and Geodetic Survey or British 
(Doodson) methods (10). 

The Coast and Geodetic Survey tidal predictions until 1964 were made on 
a mechanical analog computer having gears designed for a fixed set of frequencies. 
The predictions now made on an electronic computer do not have the above 
restriction; in this particular study, 114 constituents have been included. 

In shallow water, rhe nonlinear interaction among large-amplitude con- 
stituents generates additional constituents whose frequencies are integral 
sums or differences of the frequencies of known constituents (8). It is necessary 
to identify the important additional compound tides, include them in a new 
analysis, and then predict, using the enlarged set of harmonic constants. The 
availability of the BOMM (1) programs for time-series analysis makes some 
of these steps relatively easy. 

First, a routine 37-constituent analysis was made of 192 days of Anchorage 
hourly data for the middle of 1964. Using the derived constants, hourly heights 
were predicted and subtracted from the observations, and then a spectral anal- 
ysis was made of the residuals. This identified frequency bands of greatest 
energy in the residuals, and a Fourier analysis, using maximum resolution, 
was made for these bands. Wherever large values stood out above the continuum 



1967] Zetler and Cummings : Predicting Shallow-water Tides 



105 



10"' 



'\ 37 CONSTITUENTS 
I \ 




114 CONSTITUENTS 



5 6 7 

Frequency in cpd 



Figure 1. Spectral analysis of Anchorage residuals. 

in a plot of the Fourier amplitudes, an effort was made to identify an integral 
combination of frequencies of constituents that were known to be important 
and that closely matched the frequencies of these peaks. A new least-square 
analysis was performed, adding these new frequencies to the original 37. As 
a check, a new total prediction was prepared, new residuals were determined, 
and Fourier- and power-spectrum analyses were conducted with these data. 

Fig. 1 shows the comparative power spectra with residuals from 37 and 
114 constituents, respectively. The solid line below the dotted line shows 
that a significant improvement has been made in every species. 

Fig. 2 shows the results of Fourier analysis near two cycles per day for the 

























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CONSTITUENT SPEEDS IN °/hr. 



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Figure 2. High-resolution Fourier analysis near 2 cycles per day; Anchorage. Top: Residuals from 
37 constituents. Bottom: Residuals from 114 constituents. 



io6 



Journal of Marine Research 



[25,1 



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74 



Figure 3. High-resolution Fourier analysis near 5 cycles per day: Anchorage. Top: Residuals from 
37 constituents. Bottom: Residuals from 114. constituents. 



two sets of residuals. Although a major portion of the energy has been removed, 
it is obvious that some remains. In a recent paper on tidal cusps (7), it was 
shown that the continuum rises in cusps near the large tidal lines. There are 
indications of a systematic residual midway between the groups (identified 
by the first two digits of the Doodson number), including speeds of about 
28. 2°, 28. 7 , 29.2°, and 29. 8° per hour. Combinations of constituents sig- 
nificantly more contrived than those used would be required to approximate 
these speeds, and this has not been done because the cusps are now believed 
to include both line-line and line-noise interactions (W. H. Munk, personal 
communication). 

Fig. 3. shows a comparable Fourier analysis of the residuals near five cycles 
per day. No other study has been found in which this portion of the spectrum 
has been examined for tidal lines. There is significantly less evidence of a cusp 
in the final residuals than in Fig. 2; this could have been anticipated from the 
spectral analysis in Fig. 1. Furthermore, cusps are found adjacent to large 
tidal lines; these do not occur at five cycles per day. 

Table I identifies all of the 114 constituents and shows their amplitudes. 
The subscript at the right of the name indicates the number of cycles per day. 



1967] Zetler and Cummings : Predicting Shallow-water Tides 



107 



Table I. Anchorage Tidal Constituents. 

Name Source Doodson No. 

Sa 056.555 

Ssa 057.555 

Mm 065.455 

MSf 073.555 

Mf 075.555 

2Qj 125.755 

ff , 127.555 

Q t 135.655 

Ql 137.455 

O, 145.555 

MPj M„-P, 147.555 

Mj 155.655 

Xl 157.455 

Pj 163.555 

S, 164.555* 

K t 165.555 

J, 175.455 

2PO x 2P!-©! 181.555 

SO! S 2 -0, 183.555 

OOj 185.555 

2NS 2 2N 2 -S 2 217.755 

2NK2S 2 2N 2 + K 2 -2S 2 219.755 

MNS 2 M 2 +N 2 -S 2 227.655 

MNK2S 2 M 2 + N 2 + K 2 -2S 2 229.655 

2MS 2K 2 2M 2 + S 2 -2K 2 233.555 

2N 2 235.755 

H 2 237.555 

N 2 245.655 

v 2 247.455 

2KN2S 2 2K 2 + N 2 -2S 2 249.655 

OP 2 O, + P t 253.555 

M 2 255.555 

MKS 2 M 2 + K 2 - S 2 257.555 

M2(KS), M 2 + 2K 2 -2S 2 259.555 

2SN(MK) 2 2S 2 +N 2 -M 2 -K 2 261.655 

A 2 263.655 

L 2 265.455 

T 2 272.556 

S 2 273.555 

R 2 274.554 

K 2 275.555 

MSN 2 M 2 + S 2 - N 2 283.455 

2KM(SN) 2 2K 2 + M 2 -S 2 -N 2 287.455 

2SM 2 2S 2 -M 2 291.555 

SKM 2 S 2 + K 2 -M 2 293.555 

NO s N 2 + 0! 335.655 

* Doodson uses 164.556 with a speed of 15.0000020. 



Speed 


Amplitude 


(°M 


(feet) 


.0410686 


.519 


.0821373 


.182 


.5443747 


.139 


1.0158958 


.347 


1.0980331 


.101 


12.8542862 


.041 


12.9271398 


.129 


13.3986609 


.210 


13.4715145 


.030 


13.9430356 


1.197 


14.0251729 


.236 


14.4966939 


.169 


14.5695476 


.026 


14.9589314 


.588 


15.0000000* 


.119 


15.0410686 


2.238 


15.5854433 


.088 


15.9748272 


.060 


16.0569644 


.225 


16.1391017 


.084 


26.8794590 


.072 


26.9615963 


.136 


27.4238337 


.162 


27.5059710 


.107 


27.8039338 


.066 


27.8953548 


.368 


27.9682084 


.683 


28.4397295 


1.830 


28.5125831 


.493 


28.6040041 


.072 


28.9019669 


.145 


28.9841042 


11.039 


29.0662415 


.108 


29.1483788 


.087 


29.3734880 


.095 


29.4556253 


.274 


29.5284789 


.573 


29.9589333 


.128 


30.0000000 


2.937 


30.0410667 


.200 


30.0821373 


.922 


30.5443747 


.208 


30.7086493 


.054 


31.0158958 


.181 


31.0980331 


.073 


42.3827651 


.101 



io8 



yournal of Marine Research 



[25,1 



Table I. Anchorage Tidal Constituents (continued). 

Name Source Doodson No. Speed Amplitude 

(°/hr) (feet) 

2MK 3 f 2M 2 -K, 345.555 42.9271398 .311 

M 3 355.555 43.4761563 .084 

S0 3 Sj + O! 363.555 43.9430356 .157 

MK S M 2 + K! 365.555 44.0251729 .218 

SK 3 S 2 + K! 383.555 45.0410686 .141 

N 4 2 N 2 435.755 56.8794590 .093 

3MS 4 3M 2 -S 2 437.555 56.9523127 .117 

MN 4 M 2 + N 2 445.655 57.4238337 .280 

MNKS 4 M 2 + N 2 + K 2 -S 2 447.655 57.5059710 .085 

M 4 455.555 57.9682084 .839 

SN 4 S 2 + N 2 463.655 58.4397295 .079 

KN 4 K 2 +N 2 465.655 58.5218668 .134 

MS 4 M 2 +S 2 473.555 58.9841042 .538 

MK 4 M 2 + K 2 475.555 59.0662415 .123 

SL 4 S 2 + L 2 483.455 59.5284789 .056 

S 4 491.555 60.0000000 .061 

MN0 5 M 2 +N 2 + 0! 535.655 71.3668693 .077 

2M0 5 2M2 + 0! 545.555 71.9112440 .141 

3MP 5 3M 2 -P X 547.555 71.9933813 .064 

MNK 6 Mj + Njj + K! 555.655 72.4649023 .061 

2MP 6 2JVL. + P! 563.555 72.9271398 .134 

2MK 5 2M 2 + Kj 565.555 73.0092770 .198 

MSK 5 M 2 +S 2 + K, 583.555 74.0251728 .097 

3KM 5 K 2 + K! + M 2 585.555 74.1073100 .042 

3NKS 6 3N 2 + K 2 -S 2 627.855 85.4013258 .081 

2 NM, 2 N 2 + M 2 635.755 85.8635632 .090 

2NMKS 6 2N 2 + M 2 + K 2 -S 2 637.755 85.9457005 .102 

2MN S 2M 2 + N a 645.655 86.4079380 .281 

2MNKS 6 2M 2 +N 2 + K 2 -S 2 647.655 86.4900752 .098 

M 6 655.555 86.9523127 .507 

MSN 6 M 2 + S 2 +N 2 663.655 87.4238337 .093 

MKN 6 M 2 + K 2 +N 2 665.655 87.5059710 .127 

2MS 6 2M 2 + S 2 673.555 87.9682084 .483 

2MK, 2M 2 + K 2 675.555 88.0503457 .146 

NSK 6 N 2 +S 2 + K 2 683.655 88.5218668 .104 

2SM„ 2S 2 + M 2 691.555 88.9841042 .090 

MSK 6 M 2 + S 2 + K 2 693.555 89.0662415 .057 

S 6 6E1.555** 90.0000000 .006 

2MNO, 2M2+N2 + 0! 735.655 100.3509735 .059 

2NMK, 2N 2 + M 2 + K! 745.755 100.9046318 .079 

2MSO, 2M 2 + S 2 + O t 763.555 101.9112440 .095 

MSKO, M i +S 2 + Yi z + O l 783.555 103.0092771 .067 

2(MN) 8 2M 2 + 2N 2 835.755 114.8476674 .053 

3MN 8 3M 2 + N 2 845.655 115.3920422 .125 

3MNKS 8 3M 2 +N 2 + K 2 -S 2 847.655 115.4741795 .062 

M e 855.555 115.9364169 .160 

f 2MK3 is named MO3 in Admiralty Manual of Tides, p. 68. 

** According to Doodson code, E = +6 and 1 = — 6 above and below base 5. 



I967J 



Zetler and Cummings : Predicting Shallow-water Tides 



109 



Table I. Anchorage Tidal Constituents (continued). 
Name 



2MSN 8 2M 2 + 

2MNK 8 2M 2 + 

3MS 8 3M 2 + 

3MK 8 3M 2 + 

MSNK 8 M 2 + S 

2(MS) 8 2M 2 + 

2MSK 8 2M 2 + 

2M2NK, 2M 2 + 

3MNK, 3M 2 + 

4MK, 4M 2 + 

3MSK 9 3M 2 + 

4MN 10 4M 2 + 

M 10 5M 2 

3MNS 10 3M 2 + 

4MS 10 4M 2 + 

2MNSK 10 2M 2 + 

3M2S, 3M 2 + 

4MSK U 4M 2 + 

4MNS 12 4M 2 + 

5MS 12 5M 2 + 

3MNKS 12 3M 2 + 

4M2S,„ 4M.+ 



Durce 


Doodson No. 


Speed 


Amplitude 






(°/hr) 


(feet) 


S 2 +N 2 


863.655 


116.4079380 


.088 


N a + K 2 


865.655 


116.4900752 


.055 


s 2 


873.555 


116.9523127 


.230 


K 2 


875.555 


117.0344500 


.056 


jj+Nj + Kj 


883.655 


117.5059710 


.083 


2S 2 


891.555 


117.9682084 


.087 


S 2 + K 2 


893.555 


1 18.0503457 


.046 


2N 2 + K, 


945.755 


129.8887360 


.036 


N 2 + K t 


955.655 


130.4331108 


.015 


K, 


965.555 


130.9774855 


.023 


S 2 +K t 


983.555 


131.9933813 


.039 


N 2 


1045.655 


144.3761464 


.051 




1055.555 


144.9205211 


.055 


N 2 + S 2 


1063.655 


145.3920422 


.065 


s 2 


1073.555 


145.9364169 


.103 


N 2 + S 2 + K 2 


1085.655 


146.4900752 


.052 


2S 2 


1091.555 


146.9523127 


.060 


S 2 + K x 


1183.555 


160.9774855 


.033 


N 2 + S 2 


1263.655 


174.3761464 


.051 


s 2 


1273.555 


174.9205211 


.056 


N 2 + K 2 + S 2 


1283.655 


175.4741795 


.042 


2S 2 


1291.555 


175.9364169 


.045 



In considering the amplitudes, it is important to remember that, although a 
tidal prediction is a summation of cosine curves, the high and low waters oc- 
cur when the sum of the first derivatives is equal to zero. In the first derivative, 
each constituent is weighted according to its speed. Therefore, 2MS6, with 
an amplitude of about one-half foot, contributes as much to the times of high 
and low waters as a diurnal constituent having an amplitude of three feet. 
There are two problems concerning these results that need to be explored. 
First, as the number of interactions to obtain a particular frequency increases, 
the number of combinations that add up to this frequency also increases. For 
example, the Coast and Geodetic Survey uses 2 MK 3 for the frequency that 
is named MO 3 by the British. Although the speeds are the same, the node 
factors and phase corrections are not. In seeking to identify a peak in the high 
resolution Fourier plot, the tendency is to accept the first combination of 
constituents that satisfies the data; there may be a more logical one that has 
not been discovered and, in any case, the multiplicity of satisfactory combin- 
ations is bound to introduce some error due to the different corrections for 
the longitude of the moon's node. Inasmuch as equilibrium relationships are 
not necessarily valid, there does not seem to be any way to resolve'the problem 
except, possibly, by analyzing a large number of consecutive years of data and 
empirically determining node corrections. 



no 



"Journal of Marine Research 



[25,1 



Furthermore, are these constituents part of a stationary process? That is, 
if the harmonic constants are used for future predictions, will they fit the 
phenomena at that time? This is the characteristic that made reliable tidal 
predictions possible many years ago. The easiest way to check this point is to 
compare the harmonic constants derived from different series of data. Data 
were not available to do this for Anchorage, but the same procedure was used 
with three years of Philadelphia data (1946, 1952, and 1957) for a smaller 
set of constituents (Table II). The set of constituents was determined from 
only the 1957 data. 

Using subjective criteria, 16 of the original 37 constituents were un- 
satisfactory as compared with 9 of the added 24 constituents (roughly a similar 
ratio). Traditionally, the Coast and Geodetic Survey omits from its predictions 
analyzed constituents that have amplitudes of less than .03 foot because the 
phase tends to be unreliable for such small constituents. Of the original 16 
poor values, six are larger than .03 foot. However, five of these are long-period 
constituents (Sa, Ssa, Mm, Mf, and MSf), and it has been shown (6, 7) that 
the continuum rises sharply in the low frequencies, making the .03-foot limit 
too low in this portion of the frequency spectrum. This left one unsatisfactory 
routine constituent, 2N2, and two unsatisfactory new constituents, KN 4 
and MKN6, that were greater than .03 foot. A study of all unsatisfactory 
new constituents showed that the sum of K 2 and N 2 appeared in six of the 
nine. Furthermore, there appeared to be for these six constituents a consistent 
pattern in the phase relationships that indicated that a very small change in 



Table II. Tidal Constants; Philadelphia. 

^ Amplitude ^ 

1946 1952 1957 

(feet) (feet) (feet) 

Mm 0.187 0.067 0.048 

MSf 0.166 0.056 0.146 

Mf 0.045 0.123 0.108 

Ssa 0.129 0.123 0.153 

Sa 0.370 0.153 0.267 

MPif 0.027 0.042 0.039 

Xi\ 0.022 0.020 0.036 

KP,f 0.024 0.011 0.037 

2Q t 0.013 0.003 0.031 

Q t 0.030 0.051 0.031 

e , 0.018 0.013 0.030 

O, 0.264 0.289 0.266 

M, 0.019 0.008 0.018 

P x 0.067 0.061 0.096 

K x 0.316 0.331 0.342 

Sj 0.089 0.065 0.081 

J, 0.030 0.006 0.010 



r 


- Phase lag*- 


N 


1946 


1952 


1957 


16.3 


72.2 


335.0 


19.8 


67.9 


348.8 


80.8 


292.6 


304.6 


44.6 


115.3 


1.0 


104.5 


55.6 


91.2 


308.2 


308.2 


294.0 


119.5 


146.3 


155.4 


123.1 


355.2 


76.8 


343.0 


100.0 


140.1 


230.3 


225.2 


209.3 


225.8 


81.3 


199.8 


199.0 


198.6 


202.0 


342.0 


15.2 


252.3 


222.2 


207.7 


195.6 


212.7 


209.2 


211.1 


170.4 


175.5 


151.5 


257.5 


130.7 


108.2 



1 967 J Zetler and Cummings : Predicting Shallow-water Tides 1 1 1 

Table II. Tidal Constants, Philadelphia (continued). 

s Amplitude ^ 

1946 1952 1957 

(feet) (feet) (feet) 

OOj 0.010 0.010 0.003 

MSN 2 f 0.020 0.020 0.038 

2 N 2 0.084 0.080 0.041 

Hi 0.158 0.168 0.138 

N 2 0.403 0.425 0.417 

v., 0.143 0.145 0.120 

M 2 2.583 2.676 2.506 

A 2 0.090 0.095 0.061 

L 2 0.221 0.238 0.283 

T 2 0.032 0.026 0.015 

S 2 0.322 0.346 0.328 

R 2 0.019 0.005 0.016 

K 2 0.108 0.094 0.078 

2SM 2 0.014 0.019 0.022 

2NP 3 | 0.015 0.015 0.016 

N0 3 t 0.022 0.019 0.024 

S0 3 t 0.026 0.026 0.030 

M 3 0.025 0.029 0.014 

MK 3 0.081 0.083 0.068 

2MK 3 0.080 0.088 0.068 

ML 4 f 0.046 0.061 0.056 

SL 4 f 0.014 0.019 0.028 

MK 4 t 0.032 0.034 0.026 

MN 4 0.121 0.122 0.114 

MS 4 0.098 0.115 0.095 

M 4 0.345 0.378 0.311 

S 4 0.007 0.006 0.010 

MN0 5 t 0.022 0.022 0.017 

2M0 5 f 0.044 0.053 0.039 

2MP 6 f 0.028 0.031 0.021 

2MK 5 f 0.051 0.055 0.045 

MNK 5 f 0.018 0.023 0.020 

2MN 6 f 0.076 0.071 0.075 

2ML 6 f 0.046 0.060 0.061 

2MS„t 0.063 0.068 0.059 

MSL 6 f 0.018 0.024 0.033 

S e 0.004 0.000 0.005 

M 6 0.148 0.159 0.138 

2(MN)„t 0.018 0.022 0.015 

3MN 8 | 0.048 0.045 0.041 

3ML 8 f 0.024 0.033 0.025 

3MS 8 f 0.038 0.041 0.033 

2MSL 8 f 0.012 0.020 0.021 

M 8 0.059 0.067 0.052 

* Referred to 75°W (g). 

t Not included in original 37 constituents. 



r 


- Phase lag*- 


N 


1946 


1952 


1957 


210.2 


195.9 


205.2 


281.9 


267.4 


282.9 


332.4 


59.3 


48.5 


175.5 


164.6 


174.5 


29.8 


31.9 


31.5 


33.9 


21.8 


22.4 


47.1 


44.8 


45.3 


52.8 


58.2 


55.7 


52.2 


70.0 


56.4 


68.7 


74.9 


227.2 


83.9 


79.8 


78.2 


29.2 


191.4 


237.4 


73.9 


75.4 


60.1 


316.6 


326.7 


266.1 


143.4 


337.5 


8.2 


77.0 


100.8 


77.8 


145.4 


125.9 


131.0 


194.7 


170.3 


37.9 


124.7 


120.9 


125.6 


97.1 


95.8 


95.7 


343.5 


348.4 


337.3 


26.6 


51.8 


26.2 


17.5 


16.4 


6.2 


336.0 


334.3 


330.9 


33.6 


26.3 


25.3 


350.3 


346.1 


346.1 


359.4 


328.8 


73.5 


349.0 


342.0 


336.7 


355.3 


342.0 


346.7 


28.1 


26.6 


7.9 


7.8 


0.5 


358.1 


49.3 


313.9 


326.0 


195.5 


188.4 


179.2 


205.1 


209.0 


189.0 


243.4 


239.0 


229.5 


235.7 


272.2 


245.7 


324.7 


297.0 


33.6 


206.4 


205.0 


196.4 


108.4 


124.2 


118.1 


131.7 


129.0 


120.4 


153.5 


130.2 


117.1 


187.1 


174.3 


171.9 


183.7 


195.9 


178.4 


146.3 


146.8 


140.9 



1 1 2 Journal of Marine Research [25, 1 

speed could make the harmonic constants acceptable. The sum of M 2 and L 2 
varies from the sum of K 2 and N 2 by .ooo.°/hr (one cycle in about 4.5 years). 
These speeds are too close together to be separated with only one year of data. 
When the change in speed was made on the six constituents and the data were 
reanalyzed, the constants for all became satisfactory, leaving only 3 of the 
added 24 constituents unsatisfactory; all three are less than .03 foot. Further- 
more, a new spectral analysis of the residuals showed a lower level of energy 
in species 4, 6, and 8 — the species containing the six modified constituents — 
thereby indicating an improvement in fitting the data by virtue of the changed 
speeds. 

In retrospect, it is now obvious why the combination of M 2 and L 2 should 
have been given preference over N 2 and K 2 . In equilibrium theory, the four 
largest semidiurnal constituents are M 2 , S 2 , N 2 , and K 2 , in that order. L 2 
is only 22°/ of K 2 . Hence, the choice of species- 2 constituents was limited 
to the first four in trying various combinations to match the frequencies where 
high resolution Fourier analysis showed large peaks. However, the analysis 
for Philadelphia shows L 2 to be roughly three times larger than K 2 . There- 
fore, it is obvious that larger interactions should be expected from the sum 
of M 2 and L 2 than from N 2 and K 2 . 

Essentially then, 3 of 24 new constituents are unsatisfactory compared with 

16 of the original 37 — an amazing improvement considering that the 37 

include the major constituents that are not subject to question. These results 

raise questions as to whether some corrections in the speeds of the smaller 

standard constituents may be indicated. At one time the manpower requirements 

for successive analyses of a large number of years of data made such a study 

virtually impossible. The present availability of both computer programs for 

analysis and data in a format compatible with computers makes such a study 

now only a modest effort ; 

„, TTT . - . , plans for future tidal re- 

1 able 111. Comparisons or observations and pre- , . t-cc a mi • 

... r . / T , . _ , , r search in LbbA will in- 

dict.ons for May, July, and October 1964; dude ^ sfud 

Anchora § e - Tables III and IV 
No. of constituents in predictions 37 114 show comparisons of ob- 
Time differences (pred.-obs.) servations and predictions 
High water (hours) -0.13 -0.03 for Anchorage and Phi- 
Low water (hours) -0.35 -0.19 fcdelphia, respectively. If 

Ratio, obs./pred. t h e t i me differences were 

Mean ran S e L05 101 smaller and if the ratio 

Tide level minus sea level of observed range to pre- 

Observed (feet) -1.09 -1.09 ,. , 1 

Predicted (feet) - .70 -1.00 dlCted ran § e Were doSel " 

r. j 1 • /1 00 a , nc « to 1. 00, the fit would be 

Residual variance (192 days, 1964) ' . 

in feet 2 9767 .2954 better - Tlde level mlnus 

% of original variance 1.33 0.40 sea level is a measure of 



1967] Zetler and Cummings : Predicting Shallow-water Tides 113 

the distortion of the Table IV. Comparisons of observations and pre- 
curve from a pure cosine dictions for January, March, July, and October 

curve, primarily due to 1 957 ; Philadelphia. 

the contributions of com- _, . .... „_ _, 

No. or constituents in predictions 37 61 

pound constituents. An 

. r 111 Time differences (pred.-obs.) 

optimum ht would show High water (hours) -0.18 -0.14 

identical values for ob- Low water (hours) -0.33 -0.28 

served and predicted val- Ratio> ob s./pred. 

ues. The residual var- Mean range 1.06 1.04 

iance, which should be as Tide level minus sea level 

small as possible, is sig- Observed (feet) -0.23 -0.23 

nificant only as a com- Predicted (feet) -0.12 -0.14 

parative number. The Residual variance (355 days, 1957) 

absolute numbers depend in feet * 3467 - 3299 

., . °/ of original variance 8.49 8.08 

primarily on the range 

of tide and the energy in 

the meteorological continuum. The improvement in practical predictions by 

using more constituents is clearly shown in the results presented in Tables 

III and IV. 

The use of "harmonic" in the title warrants some explanation. Even though 

annual or seasonal node corrections (amplitude factors and phase corrections) 

are applied to lunar constituents by all organizations preparing tidal tables, 

the predictions are ordinarily regarded as harmonic if subsequent corrections 

are not added to the derived times, the heights of high and low waters, or both. 

It is used in the title of this paper in this sense to differentiate the procedure 

from Doodson's shallow-water technique (4). Doodson (2) developed a purely 

harmonic set of constituents (calling the usual method, "quasi-harmonic"), 

but he never used the method for practical tidal predictions. 



REFERENCES 



1. Bullard, E. C, F. E. Oglebay, W. H. Munk, and G. R. Miller 

1964. A user's guide to BOMM, a system of programs for the analysis of time series. 
Inst, of Geophysics and Planetary Physics, U. of Calif., La Jolla. 108 pp. 

2. Doodson, A. T. 

1921. The harmonic development of the tide-generating potential. Proc. R. Soc, (A) 100: 
305-329. 
3.1928. The analysis of tidal observations. Phil. Trans., A 227: 223-279. 

4. 1957. The analysis and prediction of tides in shallow water. Int. Hydrogr. Rev. 34(1) : 5-46. 

5. Doodson, A. T. and H. D. Warburg 

1941. Admiralty manual of tides. Hydrographic Department, Admiralty, London. 270 pp. 

6. Groves, G. W., and B. D. Zetler 

1964. The cross spectrum of sea level at San Francisco and Honolulu. J. Mar. Res., 22 (3): 
269-275. 



114 Journal of Marine Research [25, 1 

7. Munk, W. H., B. D. Zetler, and G. W. Groves 

1965. Tidal cusps. Geophys. J. R. Astr. Soc, 10: 211-219. 

8. Rauschelbach, H. 

1924. Harmonische Analyse der Gezeiter des Meeres. Arch, dtsch. Seewarte, Hamburg, 
42 (r): 114 pp. 

9. SCHUREMAN, P. 

1941. Manual of harmonic analysis and prediction of tides. Spec. Publ. H. S. est. geodet. 
Surv., g8 : 317 pp. 
ic. Zetler, B. D., and G. W. Lennon 

Evaluation tests of tidal analytical processes. UNESCO Publication on Tide Sym- 
posium at Paris. In press. 



Printed in Denmark for the Sears Foundation for Marine Research, 

Yale University, New Haven, Connecticut, U.S.A. 

Bianco Lunos Bogtrykkeri A/S, Copenhagen, Denmark 



39 



Reprinted from DEEP SEA PHOTOGRAPHY, The Johns Hopkins Univ. Press 



J. Photogrammetry applied to photography at the 
bottom 

M. D. Schuldt, C. E. Cook, and B. W. Hale U.S. Coast and Geodetic Survey, Washington, DC. 



Abstract 

Photogrammetric techniques used in stereographic aerial 
surveys are applied to deep-sea stereophotography, per- 
mitting the photoanalyst to describe the subject quanti- 
tatively. The technique and conditional requirements are 
discussed and a few contoured and cross-section examples 
are shown. Internal accuracy is approximately one part 
in 2,000. 

5-1. Introduction 

It is the purpose of this chapter to describe photogram- 
metric measurements of the relief and the size of objects 
appearing in deep-sea photographs. This technique 
requires stereographic pairs of photographs and is 
basically similar to that of aerial photogrammetry. Its 
use eliminates the uncertainties arising from comparison 
with an object of known dimensions appearing in the 
field of view and/or reliance on shadow effects. The 
application of this method does, however, impose a few 
conditions and requires some specialized equipment. 

5-2. Conditions 

Varying degrees of success in photogrammetric contour- 
ing can be achieved with varying picture quality, but for 
best results the image must be sharp and evenly lighted, 
with good contrast. These conditions are basically a 
function of equipment, system configuration, and film; 
however, deficiencies in lighting and contrast can, within 
reason, be improved upon in the photo laboratory. For 
deep-sea work, the conditions of stereophotography must 
be met by a synchronized system of two cameras and a 
light source suitably mounted on a supporting vehicle. 
This procedure cannot be replaced by the forming of a 
stereo pair from two successive photographs taken by the 
same camera, since the motion of the camera cannot be 
controlled as precisely as is done in aerial photographic 
mapping. 



The following condition is imposed on the ratio of 
base-line length to lens-subject distance. Let b be the 
distance between the lens centers of the two cameras, and 
h be the distance from the subject to the lens plane. Then, 
with all values expressed in the same units, 



fel < — </C2 

~ h ~ 



(1) 



where k\ is the lower limit imposed by the stereoscopic 
photograph measuring instrument and kj the upper limit 
imposed by the angular field of the camera lens; /; is 
limited by the transparency of the water and its actual 
value can be derived from the system geometry and the 
amount of overlap in the stereopair; b is preset — assum- 
ing a value for h — so that the ratio is within the pre- 
scribed limits. The value of h then becomes the working 
distance of the cameras from the subject. (Typical values 



are b/h = 



1 



0.25 and k 2 = 0.4.) 



5-3. Procedure 

To enable the dimensioning of any subject appearing in 
underwater stereophotographs, each frame of a stereo- 
pair is projected and viewed so that points common to 
each frame are superimposed, and the left and right 
frames are seen with the left and right eye respectively. 
There are four ways of doing this, one of which is illus- 
trated in fig. 5-1 and will be discussed; the others will 
be mentioned briefly. 

The dichromatic method 

The method illustrated in fig. 5-1 requires that each 
frame of a stereopair, whether in color or black and white, 
be printed on black-and-white, glass dipositive plates for 
use in a dichromatic multiplexing projection stereoplotter. 
One frame is then projected in red, the other in blue- 
green, and, by wearing spectacles with matching red and 
blue-green lenses, the operator can view the image in three 

69 



70 



JOHNS HOPKINS OCEANOGRAPH1C STUDIES NO. 3 1967 




Figure 5-1. Principle of the Multiplexing Stereoplotter. 
(Photo courtesy of the U.S. Geological Survey.) 



dimensions. This projection-viewing system permits, 
through filtering, the viewing of one frame with one eye 
and the other frame with the other eye. A table serves as 
the x-y plane and is perpendicular to the axis of pro- 
jection, which is the z axis. The plane of focus is parallel 
to and above this table. The scales of both the x-y plane 
and the z axis are functions of the ratio b/h. However, 
the z scale is also a function of the focal lengths of the 
photographing and projecting cameras, and hence the 
two scales can be, but are not necessarily, the same. Fig. 
5-1 shows a small circular projection screen mounted on 
a suitable fixture and aligned parallel to the image plane. 
The screen's center serves as the reference point for either 
tracking the image contours or measuring elevations. 
Directly below this point, and in contact with the table, 
is a pencil which traces the horizontal path of the reference 
point. The fixture can be moved freely in the x-y plane 
and the screen can be moved vertically, through gearing, 
by a graduated dial. The dial readings are convertible to 
true height differences from an arbitrary zero reference 
plane. Since the vertical scale can be adjusted to fit the 
vertical range of the screen, the reference point can be 
made to coincide with any desired point in the image. By 
moving the reference point along the curves of coinci- 
dence, those image elevations are sketched, and thus 
the entire relief can be contoured at any desired interval. 





H ^immm^&^jjm&iix mam 

Figure 5-2a. Pair of stereoscopic photographs, showing sand ripples. Depth, 18.3 m. Location, 35°26.7'N 75°24.0'W. July, 1963. 



DEEP-SEA PHOTOGRAPHY 



71 




Figure 5-2b. Contours drawn on one of the stereopair in fig. 
5-2a. Contour interval, 15 mm. 



Also, by moving the reference point along any horizontal 
line and adjusting it vertically — noting dial readings 
and x-y coordinates — any desired cross section of the 
image can be drawn. Fig. 5-2 shows contour map and 
section profiles constructed from the respective stereo- 
scopic pairs using the above method. Fig. 5-3a shows a 
stereoscopic pair from which the contours of fig. 5~3b 
were constructed. 

The size of the photographs and illustrations was 
altered to fit these pages. Actually, contouring is done on 
a much larger scale than shown here; somewhere in the 
neighborhood of one square meter. The contour intervals 
and cross sections shown were chosen for no other reason 
than to demonstrate the technique. Intervals could just 
as well have been larger, smaller, or irregular depending 
on the purpose. Likewise, the cross sections could have 
been located anywhere and oriented in any direction. 
Furthermore, any object, regardless of its orientation 
with respect to the coordinate system, can be dimensioned 
provided that it has sufficient definition in the projected 
image. 

The absolute accuracy of measurement of the instru- 
mentation used for preparing the accompanying drawings 
is better than one part in 2,000. Level datum or coordi- 
nate axis orientation is dependent on the assumption that 
the plane of the photograph is perpendicular to the 
gravity vector. Level data could be incorporated into the 







Figure 5-2c. Enlarged contour map of the sand ripples in fig. 5-2a. Contour interval, 15 mm 



72 



JOHNS HOPKINS OCEANOGRAPHIC STUDIES NO. 3 1967 




Figure 5-2d. Cross section along the line A-B in fig. 5-2c. 



system to verify this assumption or provide the necessary 
data to compute the angular correction. 

Other methods 

The projection-viewing method discussed above is 
referred to as the dichromatic method; there are also 
the flicker, optical, and polarized-light methods. The 
dichromatic method requires black-and-white transparen- 
cies whereas either color or black-and-white positive 
transparencies may be used in the other three. Glass 
transparencies are preferred because of their stability, 
but ordinary film may be used. 

The flicker method is a synchronized projection-viewing 
system which utilizes the image retention capabilities of 
the eyes. Alternately, the left frame is seen with the left 
eye and the right frame with the right eye, and the images 
alternate or flicker at such a rate that both frames appear 
to be viewed simultaneously, thus giving depth to the 
image. In the optical method the frames are viewed 
through an optical system to achieve image depth. The 
polarized-light method projects one frame with light 
polarized in one direction and the other frame with light 
polarized in a direction at right angles to the first. Then, 
when viewed with spectacles fitted with appropriate 
lenses, the image is seen to have depth. Contouring and 



profiling with these methods is analogous to the pro- 
cedure described above, but with modification according 
to the particular method. 

5-4. Applications 

Although any sampling system has limitations, the tech- 
niques described can be applied to the measurement of: 
ripple characteristics for interpretation of the water 
movements they reflect; bottom roughness for sonar 
studies; grading of sediments into fine, medium, and 
coarse; and the linear extent of such grades. Geological 
features can be measured, such as width and height of 
outcrops, size of fracture patterns, inclusions in con- 
glomerates, size of minor structures like nodules for 
mineral-resource evaluation studies, pillow lava, etc. 
The dimensioning of organisms for quantitative descrip- 
tion and taxonomic studies, and the measurement of 
burrows, mounds, tracks, and trails for biological studies 
are also subject to this technique. A single stereopair or 
a mosaic with stereo between adjacent pairs can be 
analyzed. The mosaic allows examination of large fea- 
tures not definable in a single pair. Further refinement 
of the system and development of operating techniques 
will extend the applications. 








Figure 5-3a. Pair of stereoscopic photographs, showing a rock. Depth 2,750 m. Location, 38°15.0'N 71°21.0'W. October, 1961. 



DEEP-SEA PHOTOGRAPHY 



73 




5-5. Summary 

A method has been described to utilize stereophotography 
beyond the usual visual sensation of three dimensions. 
Within its limitations the system permits the scientist to 
measure what he sees without being there himself or tak- 
ing samples. The method elevates deep-sea stereophotog- 
raphy to the status of a sampling device and can be used 
alone or correlated with other sampling means, permitting 
the extension of "point" information to "area" informa- 
tion. This technique allows an accurate quantitative 
description of objects and features that otherwise could 
only be described in nondimensional terms. 

To quote Lord Kelvin (1824-1907): "I often say that 
when you can measure what you are speaking about, and 
express it in numbers, you know something about it; but 
when you cannot express it in numbers, your knowledge 
is of a meagre and unsatisfactory kind; it may be the 
beginning of knowledge, but you have scarcely, in your 
thoughts, advanced to the stage of science, whatever the 
matter may be." 



Figure 5-lb. Contours drawn on one of the stereopair in 
fig. 5-3«. Contour interval, 10 mm. 



40 



Reprinted from 0CEAN0L0GY YEARBOOK, 1968, Oceanology International 



SEA-FLOOR GEOLOGY 

hi/ Dr. Harris B. Stewart jr., director. 
Institute for Oceanography, Environ- 
mental Science Services Administration 

If the world ocean is considered as a 
big flat pan of water, physical oceanog- 
raphy is concerned with the water and 
marine geology with the pan. Studies of 
this "pan" include the origin of its major 
features— trenches, mid-ocean ridges, sea- 
mounts, and submarine canyons. 

Included also are the geophysical 
studies of the earth beneath the sea, 
the big-picture research leading to more 
complete knowledge of the origin of the 
"pan" itself and of its edges— the con- 
tinental margins. 

Even the most minute characteristics 
of the sediments covering the bottom 
and sides of the ocean basin come un- 
der the scrutiny of the marine geologist. 
His tools run the gamut from expensive 
research ships and drilling rigs to scuba 
gear and a geology hammer; from ship- 
board gravity meters, towed magnetom- 
eters, and deep-sea dredging equipment 
to an underwater Brunton compass, a 
bottle of hydrochloric acid, and a pair 
of dividers. His most effective tools, how- 
ever, are an insatiable curiosity and a 
basic and sound background in geologv. 

During the last year or two, the field 
of marine geology has seen some bril- 
liant thinking leading toward the syn- 
thesis of exciting new hypotheses. We 
also have witnessed the development 
of highly complex but workable equip- 
ment that gives the marine geologist the 
means to get the data necessary to put 
these new hypotheses to the test and 
to develop what primary school teachers 
term a "basic understanding." 

Among the new hypotheses is the con- 
cept of a spreading sea floor and the 
use of the history of reversals in the 
earth's magnetic field as a means of 
verification. The long-in-disrepute Wege- 
ner hypothesis of continental drift has 
in the last few years enjoyed a renewed 
popularity based on new data and en- 
lightened thinking. Men like Tuzo Wil- 
son, Robert Dietz, and Fred Vine have 
proposed controversial ideas, and more 
marine geologists have added more think- 
ing to their traditional role of describing. 

The death of Project Mohole will be 
ascribed, when its history is written, pri- 
marily to the inability of marine geol- 
ogists to agree among themselves— a 
healthy state— and their lack of under- 
standing of the economic and political 
factors involved in major scientific projects. 



However, some significant byproducts 
resulted from Mohole— mainly the Guad- 
alupe test drilling results, and the forma- 
tion of the Joint Oceanographic Institu- 
tions Deep Earth Sampling project. 

New equipment also has given impe- 
tus to the field of marine geology. Most 
important here is the satellite naviga- 
tion system, bv which research and sur- 
vey ships can determine position with 
remarkable accuracy. 

When supplemented by other long- 
range navigation methods, the system 
will make it possible to obtain highly- 
accurate, tight-grid, detailed survevs of 
such features as the mid-ocean ridge- 
and-rift systems. 

Seismic reflection profilers have pro- 
vided the third dimension to geological 
investigations at sea, and the next few 
years should see improved models in- 
stalled as standard equipment on all 
research and survey vessels. Similarly, 
the boom in manned submersibles for 
marine geological research will produce 
new knowledge as more geologists are 
able to observe the sea floor and its 
processes at close range. 

The report, "Effective Use of the 
Sea," by the President's Science Advis- 
ors Committee's Panel on Oceanogra- 
phy (PSAC-POO), downgraded the sys- 
tematic survey as a research technique. 
This, in effect, has halted for the next 
year or so the highly productive surveys 
of the Pacific sea floor. 

Such results can come only from the 
accurately controlled systematic surveys 
that government vessels do so well. 

Hopefully, the systematic survey will be 
reinstated as one of the most valuable 
techniques available to the marine geol- 
ogist who is interested in learning of the 
origin of the ocean basins. 

The push for the economic recovery 
of sea-floor minerals and the need for 
data on the mass physical properties 
of marine sediments should result in 
increased work in these areas over the 
next few years. 

We can be sure that new tools and 
the increasing ratio of tKnking to de- 
scribing in marine geology should result 
in important contributions to our knowl- 
edge of "the pan" that holds the waters 
of the ocean. □ 







This article is offered to members 
of the ESSA family in the hope that 
it will make their summer vaca- 
tions safer and happier. 






Reprinted from ESSA WORLD July, 1967 



This summer, make 
sure you outwit the 



KILLER AT THE 
SEASHORE 



I his summer your child could drown 
— needlessly — at the seashore. 

He may be an able swimmer. He may 
be in very shallow water perhaps only up 
to his chin. It is a warm sunny day, with 
a good surf running. Lots of other chil- 
dren are playing in the shallows, and 
tragedy seems far removed. 

But suddenly, and quite unexpectedly, 
he may feel the bottom moving fast 
beneath his feet and realize he is being 
swept out to sea. Knowing that he can 
swim well, he may strike out hard against 
the current for shore. But after a few 
minutes, he will find that he is not mak- 
ing any headway, that the water around 
him is over his head, that he is almost 
out to the surf zone. 

He may call for help, but no one will 
hear him above the surf's roar. Panic 
will take over, along with exhaustion, and 
maybe a bad cramp. And in another 
moment, he will be dead by drowning. 

Every year, many persons unfamiliar 

BY HARRIS B. STEWART, JR. 

Acting Director, ESSA Institute 

for Oceanography 






with rip currents lose their lives un- 
necessarily. 

They may be excellent swimmers, but 
they may not know what to do when 
caught in a rip current. And they will 
die, as victims of killer currents, in fact, 
but as victims of the exhaustion and 
panic that would never have occurred 
if more swimmers know how to recognize 
a rip current and how relatively easy it 
is to swim out of one. 

The Institute for Oceanography has 
gathered and facts about rip currents 
that endanger the lives of swimmers 
and developed some simple rules of cop- 
ing with them. It would be useful, and 
even life-saving, for 
every swimmer to 
know them as he 
prepares to take a 
summer vacation at 
the beach. 
I What is a rip cur- 
JJ rent? Technically 
I speaking, it is a 
strong narrow cur- 
rent flowing out to 
£__ sea perpendicular to 



30 




the shore and carrying back to sea the 
water brought in by waves and longshore 
currents. It is part of a generally-circular 
pattern of water movement found off 
most long, gently-sloping sand beaches. 
It can travel at speeds up to two or even 
three miles an hour, and change its posi- 
tion from day to day and even during 
the same day. The same beach may have 
several rip currents operating at one 
time, and then go weeks with none at all. 
Once outside the surf zone, the rip 
current dies rapidly, spreads out, and 
often forms a big sluggish eddy which 
oceanographers call a "rip head". 
How do you recognize a rip current? 
Rip currents are usually easy to see once 
you know what to look for. In general, 
the pattern of the sea surface between 
the beach and the area where the waves 
are breaking offshore, is one of long lines 
that run parallel to the beach. A rip 
current makes a break in this pattern by 
providing a cross-pattern line running 
perpendicular to the beach. Sometimes 
small choppy waves form a line out to 
the surf zone indicating a rip current. 
Often, a foam line will show where it is. 



Photo courtesy American Airlines 



At other times, when there is suspended 
sediment in the water, a rip current may 
be marked by a long brownish band of 
darker water. 

Usually the surf is lower where a rip 
current passes through the surf zone, 
and there will be a break in the line of 
breakers. Or if a rip current has been 
stabilized in one place for a while, there 
is often a short sand spit built out from 
the beach at the base of the rip. 

If, as you are swimming, you notice 
that you tend to move faster in one direc- 
tion along the shore, there are probably 
strong longshore currents, and you should 
expect rip currents to be developing. Or 
if you are walking from the beach into 
shallow water, and you feel a longshore 
current pulling at your legs, you may be 
able to see a spot down-current where a 
rip is moving water seaward. Or look at 
the outer end of any jettv. groin, or other 
solid obstruction to the longshore move- 
ment of water, and there likely will be 
a rip current where the water has been 
deflected seaward. 

How do you get out of a rip current? 
Fortunately, you will know when you 
are in one. Your first indication, if your 
feet touch bottom occasionally, will be a 
feeling that the bottom is moving fast 
toward shore. It's a strange feeling, for 
you have no nearby frame of reference 
to show that you yourself are moving, 
and you feel as though the sand beneath 
your feet is moving. When your feet 
aren't occasionally touching bottom, you 
will soon notice that you are much fur- 
ther out to sea than you expected to be. 
or moving out faster than other swim- 
mers near you. or that the area where 
the waves are breaking seems to be ap- 
proaching fast. 

This is the point where most swimmers 
who lose their lives start swimming their 
hardest toward the beach and where they 
make a fatal mistake. Since the rip cur- 
rent is seldom more than ten or twenty 
feet wide, swimmers should swim parallel 
to tlie beach, and they can very soon be 
out of it. 

An alternative is to relax and let the 
current carry you seaward through the 
surf zone and into the rip head where 
the current slows down, and from where 
you can then have a leisurely swim back 
to the beach on a course parallel to the 
rip current. Surfers along the California 
coast actually search out rip currents and 
ride them on their boards back out 
through the surf zone to the place where 
the big ones are humping up. 

The rules are simple. Knowing them 
may save your life: (1) Learn to recog- 
nize a rip current: (2) Look for them 
every time you go to the beach: (3) 
Point them out to the children and tell 
them about them: (4) Avoid them if 
possible: but (5) If you do get caught in 
one. swim parallel to the beach, and you 
will soon be out of it. □ 








•&Z£r£ 






*£ 





Photo courtesy Mia 



-Metro News Bureau 

31 



Reprinted from THE MIAMIAN, September 196? 



42 




ea 
cience 

hips 



Dr. Stewart is the director of the ESSA 
(Environmental Sciences Services Ad- 
ministration) east coast oceanography 
laboratory which will soon be built on 
Virginia Key. Berthing facilities for 
ESSA's ships and other necessary build- 
ings will be constructed at the new Port 
of Miami on Dodge Island. Dr. Stewart 
tells of their plans. 

The MIAMIAN • September, 1967 




By Dr. Harris B. Stewart, Jr. 

Even as the New Port of Miami on Dodge Island it- 
self is taking shape, so too are the plans for its use as a 
major staging area for oceanographic research ships. In 
mid-August Admiral John Bull and Captain Allen 
Powell of ESSA's Coast and Geodetic Survey came to 
Miami to work out construction schedules for the Dodge 
Island facility with Port Director Irvin Stephens. Their 
plans are the result of several months of discussions with 
officials of the Institute of Marine Science of the Uni- 
versity of Miami and of the Bureau of Commercial Fish- 
eries' Tropical Atlantic Biological Laboratory. It is 
hoped that the oceanographic ship facility on Dodge Is- 
land will meet the combined requirements of these three 
major oceanographic research organizations. 

The details of the plans are not yet sufficiently worked 
out to warrant publication. However, the university, the 
federal agencies and the Port of Miami are working 
together to come up with a facility that will not only 
meet the requirements for the ships to base there but 
will also fit in architecturally with the other structures 
already built or planned for the new Port of Miami. 

The Coast and Geodetic Survey ship DISCOVERER, 
which visited Miami the end of July, officially trans- 
ferred from Jacksonville, where she was constructed, to 
Miami on August 28th. Until the oceanographic ship 
facility on the south side of Dodge Island is completed, 
she will berth on the north side of the island. This ship is 
the major research ship of the ESSA Institute for Ocea- 
nography which last winter chose Virginia Key as the 
site for its East Coast Laboratory. Located temporarily 
at 901 South Miami Avenue, scientists of the Institute for 
Oceanography will start using the DISCOVERER this 

The MIAMIAN • September, 1967 



fall for their research work at sea. In a bit over a year, 
the DISCOVERER will be joined by a second ESSA 
ship, the RESEARCHER, now being constructed at 
Lorraine, Ohio. This newer ship will be a slightly scaled 
down version of the DISCO, as we call her, and will also 
have the Port of Miami on Dodge Island as her home 
port. From time to time, other ESSA ships will be based 
out of the Port of Miami as a logistic support port while 
they are doing research or survey work in Florida waters. 

The UNDAUNTED of the Tropical Atlantic Bio- 
logical Laboratory on Virginia Key will also base at 
Dodge Island. Hopefully, too, the ships PILLSBURY 
and GERDA of the Institute of Marine Science of U.M. 
will be part of the Port of Miami Oceanography fleet. 
These three marine research activities, ESSA, TABL, 
and IMS, together with the Miami Seaquarium form the 
nucleus of the Virginia Key Marine Science Complex. 
The Seaquarium's vessels are berthed there at the Vir- 
ginia Key site, but there is insufficient depth of water for 
the larger research ships. 

The Port of Miami facility has the water for these 
larger ships. When the south side of the island is bulk- 
headed and the power, fresh water, and other services 
are in, the oceanographic ships will have the place to tie 
up they so badly need. By then the shoreside construc- 
tion on Dodge Island will be completed, and Miami will 
have the finest oceanographic ship facility on the east- 
ern seaboard. 

Dodge Island is gradually rising from the floor of 
Biscayne Bay. The ships are here or under construction. 
Plans for the buildings, bulkheads, and support services 
are well along. The next few years will be exciting ones 
for Dodge Island, for Miami, and for oceanography. 

27 



GPO 849 - 483 



PENN STATE UNIVERSITY LIBRARIES